Photo The Daily Galaxy

CPBM Objectives (chapter 8)

1) Identify fire behavior terms2) Explain the fire triangle3) Discuss the major elements of the fire

environment4) List and explain the three methods of

heat transfer5) List fuel characteristics which govern

combustion

CPBM Objectives (chapter 8)

6) Identify Fuel Models and examples in Florida

7) Explain the difference between fire intensity and severity and how both can be regulated and measured

8) Define residence time and why it is significant in Rx fire

9) Discuss indicators of erratic or potentially erratic fire behavior

Wind

REAR

LEFT

FLANK

RIGHT FLA

NK

FINGER

HEAD

SPOT FIRE

POCKET

UNBURNED ISLAND

Surface Fire Burning in surface fuels Grass shrubs litter

Ground Fire Smoldering in ground fuels duff peat roots stumps

Crown Fire Burning in aerial fuels Crowns or canopy of the overstory May or may not be independent of surface fire

Photo Univ of Toronto Fier Lab

Photo News Provider

Spotting ndash burning or glowing embers being transported in the air

Torching ndash Movement of fire from the surface to the crowns of individual trees

Flare Up ndash A sudden increase in ROS and Intensity

Fuel Oxygen

Heat

The Fire TriangleThe Fire Triangle

Energy release in the form of heat and light when oxygen combines Energy release in the form of heat and light when oxygen combines with a combustible material (fuel) at a suitably high temperaturewith a combustible material (fuel) at a suitably high temperature

Photosynthesis converts radiant energy to stored chemical energy (CO2 + H2O ---light-----gt C6H12O6 + O2)

Combustion reverses photosynthesis(C6H12O6 + O2 ---high temperature-----gt H2O + CO2 + heat and light)

(fuel) (325 C for wood)

Same process as decay and decomposition Begins with endothermic reaction becomes exothermic Produces thermal radiant and kinetic energy

Extinction insufficient heat to sustain combustion

HEAT

WATER ampORGANICGASES

Pre-Ignition

VISIBLE SMOKE

Smoldering

CO CO2

Glowing

2CO WATER

VISIBLE SMOKE

Flaming

4 Phases of Combustion

Pre-ignition Requires heatenergy input to

increase surface temperature gt200˚C

Dehydration Volatilization of waxes oils other

extractives Pyrolysis (chemical decomposition of

organic matter without Oxygenndash inside fuels emits volatiles)

Volatiles either condense into particles (smoke) or are consumed during flaming combustion

HEAT

WATER ampORGANICGASES

Pre-Ignition

Ignition Transition to flaming

combustion gases released by pyrolysis ignite

Surface temperatures around 320 C (600F)

Heat released by combustion brings other fuels to ignition

Flaming combustion Surface temperatures 200- 500˚

C Combustible volatiles ignite

above surface creating flame the GASES are burning not the fuel itself

Combustion occurs in zone above fuel surface

Oxidation produces heat CO2 H2O and incompletely degraded organic compounds

Smoke includes these + other gases which condense or reform above flame zone

2CO WATER

VISIBLE SMOKE

Flaming

Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas

production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other

compounds Smoldering duff and ground fires raise

soil temperature and can kill roots Large quantities of smoke

VISIBLE SMOKE

Smoldering

A result of incomplete combustion Major constituents

Particulate matter Solid or liquid particle suspended in

atmosphere Condensed hydrocarbons and tar

materials Entrained fragments of vegetation and

ash CO2 and CO H2O Gaseous hydrocarbons

Smokevolume burned increases for Low intensity fires in moist or living

fuels High rates of spread (amp less efficient

combustion)

CO CO2

GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains

Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to

fuel surface only

Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions

Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel

surface onlysurface only

Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions

Convection Vertical (or other direction)

movement of gas or liquid as heat rises

Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven

Carries firebrands away from fire spotting potential

Can create enormous columns and drive fire behavior

ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of

gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires

and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven

Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential

Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior

Heat Transfer ProcessesHeat Transfer Processes

ConductionConduction Transfer by molecular activity Transfer by molecular activity

withinwithin a solid object a solid object Primary method for raising Primary method for raising

temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels

that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels

requiring additional heat to reach requiring additional heat to reach ignitionignition

Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)

Residency Time Duration for flaming combustion to pass a specific location

Flame Length amp Depth

Residency Time = Flame DepthROS

Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-

1)

I = hwr

I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread

Flame Length is a good estimate of intensity

Severity Impact of fire on the environment Plants animals soils water

SE

VE

RIT

Y

INTENSITY

LOW

HIGH

HIGHLOW

Backing fire in long unburned longleaf pine

Stand replacing fire in mixed conifer forests

Head fire in frequently burned longleaf pine

Chaparral Brush Fires

1 Weather

2 Fuels 3 Topography

Surface Fuels Grasses Shrubs Litter (leaves)

Woody debris

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

CPBM Objectives (chapter 8)

1) Identify fire behavior terms2) Explain the fire triangle3) Discuss the major elements of the fire

environment4) List and explain the three methods of

heat transfer5) List fuel characteristics which govern

combustion

CPBM Objectives (chapter 8)

6) Identify Fuel Models and examples in Florida

7) Explain the difference between fire intensity and severity and how both can be regulated and measured

8) Define residence time and why it is significant in Rx fire

9) Discuss indicators of erratic or potentially erratic fire behavior

Wind

REAR

LEFT

FLANK

RIGHT FLA

NK

FINGER

HEAD

SPOT FIRE

POCKET

UNBURNED ISLAND

Surface Fire Burning in surface fuels Grass shrubs litter

Ground Fire Smoldering in ground fuels duff peat roots stumps

Crown Fire Burning in aerial fuels Crowns or canopy of the overstory May or may not be independent of surface fire

Photo Univ of Toronto Fier Lab

Photo News Provider

Spotting ndash burning or glowing embers being transported in the air

Torching ndash Movement of fire from the surface to the crowns of individual trees

Flare Up ndash A sudden increase in ROS and Intensity

Fuel Oxygen

Heat

The Fire TriangleThe Fire Triangle

Energy release in the form of heat and light when oxygen combines Energy release in the form of heat and light when oxygen combines with a combustible material (fuel) at a suitably high temperaturewith a combustible material (fuel) at a suitably high temperature

Photosynthesis converts radiant energy to stored chemical energy (CO2 + H2O ---light-----gt C6H12O6 + O2)

Combustion reverses photosynthesis(C6H12O6 + O2 ---high temperature-----gt H2O + CO2 + heat and light)

(fuel) (325 C for wood)

Same process as decay and decomposition Begins with endothermic reaction becomes exothermic Produces thermal radiant and kinetic energy

Extinction insufficient heat to sustain combustion

HEAT

WATER ampORGANICGASES

Pre-Ignition

VISIBLE SMOKE

Smoldering

CO CO2

Glowing

2CO WATER

VISIBLE SMOKE

Flaming

4 Phases of Combustion

Pre-ignition Requires heatenergy input to

increase surface temperature gt200˚C

Dehydration Volatilization of waxes oils other

extractives Pyrolysis (chemical decomposition of

organic matter without Oxygenndash inside fuels emits volatiles)

Volatiles either condense into particles (smoke) or are consumed during flaming combustion

HEAT

WATER ampORGANICGASES

Pre-Ignition

Ignition Transition to flaming

combustion gases released by pyrolysis ignite

Surface temperatures around 320 C (600F)

Heat released by combustion brings other fuels to ignition

Flaming combustion Surface temperatures 200- 500˚

C Combustible volatiles ignite

above surface creating flame the GASES are burning not the fuel itself

Combustion occurs in zone above fuel surface

Oxidation produces heat CO2 H2O and incompletely degraded organic compounds

Smoke includes these + other gases which condense or reform above flame zone

2CO WATER

VISIBLE SMOKE

Flaming

Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas

production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other

compounds Smoldering duff and ground fires raise

soil temperature and can kill roots Large quantities of smoke

VISIBLE SMOKE

Smoldering

A result of incomplete combustion Major constituents

Particulate matter Solid or liquid particle suspended in

atmosphere Condensed hydrocarbons and tar

materials Entrained fragments of vegetation and

ash CO2 and CO H2O Gaseous hydrocarbons

Smokevolume burned increases for Low intensity fires in moist or living

fuels High rates of spread (amp less efficient

combustion)

CO CO2

GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains

Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to

fuel surface only

Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions

Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel

surface onlysurface only

Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions

Convection Vertical (or other direction)

movement of gas or liquid as heat rises

Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven

Carries firebrands away from fire spotting potential

Can create enormous columns and drive fire behavior

ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of

gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires

and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven

Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential

Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior

Heat Transfer ProcessesHeat Transfer Processes

ConductionConduction Transfer by molecular activity Transfer by molecular activity

withinwithin a solid object a solid object Primary method for raising Primary method for raising

temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels

that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels

requiring additional heat to reach requiring additional heat to reach ignitionignition

Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)

Residency Time Duration for flaming combustion to pass a specific location

Flame Length amp Depth

Residency Time = Flame DepthROS

Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-

1)

I = hwr

I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread

Flame Length is a good estimate of intensity

Severity Impact of fire on the environment Plants animals soils water

SE

VE

RIT

Y

INTENSITY

LOW

HIGH

HIGHLOW

Backing fire in long unburned longleaf pine

Stand replacing fire in mixed conifer forests

Head fire in frequently burned longleaf pine

Chaparral Brush Fires

1 Weather

2 Fuels 3 Topography

Surface Fuels Grasses Shrubs Litter (leaves)

Woody debris

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

CPBM Objectives (chapter 8)

6) Identify Fuel Models and examples in Florida

7) Explain the difference between fire intensity and severity and how both can be regulated and measured

8) Define residence time and why it is significant in Rx fire

9) Discuss indicators of erratic or potentially erratic fire behavior

Wind

REAR

LEFT

FLANK

RIGHT FLA

NK

FINGER

HEAD

SPOT FIRE

POCKET

UNBURNED ISLAND

Surface Fire Burning in surface fuels Grass shrubs litter

Ground Fire Smoldering in ground fuels duff peat roots stumps

Crown Fire Burning in aerial fuels Crowns or canopy of the overstory May or may not be independent of surface fire

Photo Univ of Toronto Fier Lab

Photo News Provider

Spotting ndash burning or glowing embers being transported in the air

Torching ndash Movement of fire from the surface to the crowns of individual trees

Flare Up ndash A sudden increase in ROS and Intensity

Fuel Oxygen

Heat

The Fire TriangleThe Fire Triangle

Energy release in the form of heat and light when oxygen combines Energy release in the form of heat and light when oxygen combines with a combustible material (fuel) at a suitably high temperaturewith a combustible material (fuel) at a suitably high temperature

Photosynthesis converts radiant energy to stored chemical energy (CO2 + H2O ---light-----gt C6H12O6 + O2)

Combustion reverses photosynthesis(C6H12O6 + O2 ---high temperature-----gt H2O + CO2 + heat and light)

(fuel) (325 C for wood)

Same process as decay and decomposition Begins with endothermic reaction becomes exothermic Produces thermal radiant and kinetic energy

Extinction insufficient heat to sustain combustion

HEAT

WATER ampORGANICGASES

Pre-Ignition

VISIBLE SMOKE

Smoldering

CO CO2

Glowing

2CO WATER

VISIBLE SMOKE

Flaming

4 Phases of Combustion

Pre-ignition Requires heatenergy input to

increase surface temperature gt200˚C

Dehydration Volatilization of waxes oils other

extractives Pyrolysis (chemical decomposition of

organic matter without Oxygenndash inside fuels emits volatiles)

Volatiles either condense into particles (smoke) or are consumed during flaming combustion

HEAT

WATER ampORGANICGASES

Pre-Ignition

Ignition Transition to flaming

combustion gases released by pyrolysis ignite

Surface temperatures around 320 C (600F)

Heat released by combustion brings other fuels to ignition

Flaming combustion Surface temperatures 200- 500˚

C Combustible volatiles ignite

above surface creating flame the GASES are burning not the fuel itself

Combustion occurs in zone above fuel surface

Oxidation produces heat CO2 H2O and incompletely degraded organic compounds

Smoke includes these + other gases which condense or reform above flame zone

2CO WATER

VISIBLE SMOKE

Flaming

Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas

production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other

compounds Smoldering duff and ground fires raise

soil temperature and can kill roots Large quantities of smoke

VISIBLE SMOKE

Smoldering

A result of incomplete combustion Major constituents

Particulate matter Solid or liquid particle suspended in

atmosphere Condensed hydrocarbons and tar

materials Entrained fragments of vegetation and

ash CO2 and CO H2O Gaseous hydrocarbons

Smokevolume burned increases for Low intensity fires in moist or living

fuels High rates of spread (amp less efficient

combustion)

CO CO2

GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains

Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to

fuel surface only

Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions

Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel

surface onlysurface only

Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions

Convection Vertical (or other direction)

movement of gas or liquid as heat rises

Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven

Carries firebrands away from fire spotting potential

Can create enormous columns and drive fire behavior

ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of

gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires

and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven

Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential

Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior

Heat Transfer ProcessesHeat Transfer Processes

ConductionConduction Transfer by molecular activity Transfer by molecular activity

withinwithin a solid object a solid object Primary method for raising Primary method for raising

temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels

that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels

requiring additional heat to reach requiring additional heat to reach ignitionignition

Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)

Residency Time Duration for flaming combustion to pass a specific location

Flame Length amp Depth

Residency Time = Flame DepthROS

Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-

1)

I = hwr

I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread

Flame Length is a good estimate of intensity

Severity Impact of fire on the environment Plants animals soils water

SE

VE

RIT

Y

INTENSITY

LOW

HIGH

HIGHLOW

Backing fire in long unburned longleaf pine

Stand replacing fire in mixed conifer forests

Head fire in frequently burned longleaf pine

Chaparral Brush Fires

1 Weather

2 Fuels 3 Topography

Surface Fuels Grasses Shrubs Litter (leaves)

Woody debris

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Wind

REAR

LEFT

FLANK

RIGHT FLA

NK

FINGER

HEAD

SPOT FIRE

POCKET

UNBURNED ISLAND

Surface Fire Burning in surface fuels Grass shrubs litter

Ground Fire Smoldering in ground fuels duff peat roots stumps

Crown Fire Burning in aerial fuels Crowns or canopy of the overstory May or may not be independent of surface fire

Photo Univ of Toronto Fier Lab

Photo News Provider

Spotting ndash burning or glowing embers being transported in the air

Torching ndash Movement of fire from the surface to the crowns of individual trees

Flare Up ndash A sudden increase in ROS and Intensity

Fuel Oxygen

Heat

The Fire TriangleThe Fire Triangle

Energy release in the form of heat and light when oxygen combines Energy release in the form of heat and light when oxygen combines with a combustible material (fuel) at a suitably high temperaturewith a combustible material (fuel) at a suitably high temperature

Photosynthesis converts radiant energy to stored chemical energy (CO2 + H2O ---light-----gt C6H12O6 + O2)

Combustion reverses photosynthesis(C6H12O6 + O2 ---high temperature-----gt H2O + CO2 + heat and light)

(fuel) (325 C for wood)

Same process as decay and decomposition Begins with endothermic reaction becomes exothermic Produces thermal radiant and kinetic energy

Extinction insufficient heat to sustain combustion

HEAT

WATER ampORGANICGASES

Pre-Ignition

VISIBLE SMOKE

Smoldering

CO CO2

Glowing

2CO WATER

VISIBLE SMOKE

Flaming

4 Phases of Combustion

Pre-ignition Requires heatenergy input to

increase surface temperature gt200˚C

Dehydration Volatilization of waxes oils other

extractives Pyrolysis (chemical decomposition of

organic matter without Oxygenndash inside fuels emits volatiles)

Volatiles either condense into particles (smoke) or are consumed during flaming combustion

HEAT

WATER ampORGANICGASES

Pre-Ignition

Ignition Transition to flaming

combustion gases released by pyrolysis ignite

Surface temperatures around 320 C (600F)

Heat released by combustion brings other fuels to ignition

Flaming combustion Surface temperatures 200- 500˚

C Combustible volatiles ignite

above surface creating flame the GASES are burning not the fuel itself

Combustion occurs in zone above fuel surface

Oxidation produces heat CO2 H2O and incompletely degraded organic compounds

Smoke includes these + other gases which condense or reform above flame zone

2CO WATER

VISIBLE SMOKE

Flaming

Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas

production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other

compounds Smoldering duff and ground fires raise

soil temperature and can kill roots Large quantities of smoke

VISIBLE SMOKE

Smoldering

A result of incomplete combustion Major constituents

Particulate matter Solid or liquid particle suspended in

atmosphere Condensed hydrocarbons and tar

materials Entrained fragments of vegetation and

ash CO2 and CO H2O Gaseous hydrocarbons

Smokevolume burned increases for Low intensity fires in moist or living

fuels High rates of spread (amp less efficient

combustion)

CO CO2

GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains

Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to

fuel surface only

Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions

Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel

surface onlysurface only

Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions

Convection Vertical (or other direction)

movement of gas or liquid as heat rises

Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven

Carries firebrands away from fire spotting potential

Can create enormous columns and drive fire behavior

ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of

gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires

and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven

Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential

Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior

Heat Transfer ProcessesHeat Transfer Processes

ConductionConduction Transfer by molecular activity Transfer by molecular activity

withinwithin a solid object a solid object Primary method for raising Primary method for raising

temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels

that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels

requiring additional heat to reach requiring additional heat to reach ignitionignition

Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)

Residency Time Duration for flaming combustion to pass a specific location

Flame Length amp Depth

Residency Time = Flame DepthROS

Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-

1)

I = hwr

I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread

Flame Length is a good estimate of intensity

Severity Impact of fire on the environment Plants animals soils water

SE

VE

RIT

Y

INTENSITY

LOW

HIGH

HIGHLOW

Backing fire in long unburned longleaf pine

Stand replacing fire in mixed conifer forests

Head fire in frequently burned longleaf pine

Chaparral Brush Fires

1 Weather

2 Fuels 3 Topography

Surface Fuels Grasses Shrubs Litter (leaves)

Woody debris

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Surface Fire Burning in surface fuels Grass shrubs litter

Ground Fire Smoldering in ground fuels duff peat roots stumps

Crown Fire Burning in aerial fuels Crowns or canopy of the overstory May or may not be independent of surface fire

Photo Univ of Toronto Fier Lab

Photo News Provider

Spotting ndash burning or glowing embers being transported in the air

Torching ndash Movement of fire from the surface to the crowns of individual trees

Flare Up ndash A sudden increase in ROS and Intensity

Fuel Oxygen

Heat

The Fire TriangleThe Fire Triangle

Energy release in the form of heat and light when oxygen combines Energy release in the form of heat and light when oxygen combines with a combustible material (fuel) at a suitably high temperaturewith a combustible material (fuel) at a suitably high temperature

Photosynthesis converts radiant energy to stored chemical energy (CO2 + H2O ---light-----gt C6H12O6 + O2)

Combustion reverses photosynthesis(C6H12O6 + O2 ---high temperature-----gt H2O + CO2 + heat and light)

(fuel) (325 C for wood)

Same process as decay and decomposition Begins with endothermic reaction becomes exothermic Produces thermal radiant and kinetic energy

Extinction insufficient heat to sustain combustion

HEAT

WATER ampORGANICGASES

Pre-Ignition

VISIBLE SMOKE

Smoldering

CO CO2

Glowing

2CO WATER

VISIBLE SMOKE

Flaming

4 Phases of Combustion

Pre-ignition Requires heatenergy input to

increase surface temperature gt200˚C

Dehydration Volatilization of waxes oils other

extractives Pyrolysis (chemical decomposition of

organic matter without Oxygenndash inside fuels emits volatiles)

Volatiles either condense into particles (smoke) or are consumed during flaming combustion

HEAT

WATER ampORGANICGASES

Pre-Ignition

Ignition Transition to flaming

combustion gases released by pyrolysis ignite

Surface temperatures around 320 C (600F)

Heat released by combustion brings other fuels to ignition

Flaming combustion Surface temperatures 200- 500˚

C Combustible volatiles ignite

above surface creating flame the GASES are burning not the fuel itself

Combustion occurs in zone above fuel surface

Oxidation produces heat CO2 H2O and incompletely degraded organic compounds

Smoke includes these + other gases which condense or reform above flame zone

2CO WATER

VISIBLE SMOKE

Flaming

Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas

production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other

compounds Smoldering duff and ground fires raise

soil temperature and can kill roots Large quantities of smoke

VISIBLE SMOKE

Smoldering

A result of incomplete combustion Major constituents

Particulate matter Solid or liquid particle suspended in

atmosphere Condensed hydrocarbons and tar

materials Entrained fragments of vegetation and

ash CO2 and CO H2O Gaseous hydrocarbons

Smokevolume burned increases for Low intensity fires in moist or living

fuels High rates of spread (amp less efficient

combustion)

CO CO2

GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains

Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to

fuel surface only

Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions

Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel

surface onlysurface only

Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions

Convection Vertical (or other direction)

movement of gas or liquid as heat rises

Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven

Carries firebrands away from fire spotting potential

Can create enormous columns and drive fire behavior

ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of

gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires

and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven

Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential

Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior

Heat Transfer ProcessesHeat Transfer Processes

ConductionConduction Transfer by molecular activity Transfer by molecular activity

withinwithin a solid object a solid object Primary method for raising Primary method for raising

temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels

that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels

requiring additional heat to reach requiring additional heat to reach ignitionignition

Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)

Residency Time Duration for flaming combustion to pass a specific location

Flame Length amp Depth

Residency Time = Flame DepthROS

Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-

1)

I = hwr

I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread

Flame Length is a good estimate of intensity

Severity Impact of fire on the environment Plants animals soils water

SE

VE

RIT

Y

INTENSITY

LOW

HIGH

HIGHLOW

Backing fire in long unburned longleaf pine

Stand replacing fire in mixed conifer forests

Head fire in frequently burned longleaf pine

Chaparral Brush Fires

1 Weather

2 Fuels 3 Topography

Surface Fuels Grasses Shrubs Litter (leaves)

Woody debris

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Spotting ndash burning or glowing embers being transported in the air

Torching ndash Movement of fire from the surface to the crowns of individual trees

Flare Up ndash A sudden increase in ROS and Intensity

Fuel Oxygen

Heat

The Fire TriangleThe Fire Triangle

Energy release in the form of heat and light when oxygen combines Energy release in the form of heat and light when oxygen combines with a combustible material (fuel) at a suitably high temperaturewith a combustible material (fuel) at a suitably high temperature

Photosynthesis converts radiant energy to stored chemical energy (CO2 + H2O ---light-----gt C6H12O6 + O2)

Combustion reverses photosynthesis(C6H12O6 + O2 ---high temperature-----gt H2O + CO2 + heat and light)

(fuel) (325 C for wood)

Same process as decay and decomposition Begins with endothermic reaction becomes exothermic Produces thermal radiant and kinetic energy

Extinction insufficient heat to sustain combustion

HEAT

WATER ampORGANICGASES

Pre-Ignition

VISIBLE SMOKE

Smoldering

CO CO2

Glowing

2CO WATER

VISIBLE SMOKE

Flaming

4 Phases of Combustion

Pre-ignition Requires heatenergy input to

increase surface temperature gt200˚C

Dehydration Volatilization of waxes oils other

extractives Pyrolysis (chemical decomposition of

organic matter without Oxygenndash inside fuels emits volatiles)

Volatiles either condense into particles (smoke) or are consumed during flaming combustion

HEAT

WATER ampORGANICGASES

Pre-Ignition

Ignition Transition to flaming

combustion gases released by pyrolysis ignite

Surface temperatures around 320 C (600F)

Heat released by combustion brings other fuels to ignition

Flaming combustion Surface temperatures 200- 500˚

C Combustible volatiles ignite

above surface creating flame the GASES are burning not the fuel itself

Combustion occurs in zone above fuel surface

Oxidation produces heat CO2 H2O and incompletely degraded organic compounds

Smoke includes these + other gases which condense or reform above flame zone

2CO WATER

VISIBLE SMOKE

Flaming

Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas

production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other

compounds Smoldering duff and ground fires raise

soil temperature and can kill roots Large quantities of smoke

VISIBLE SMOKE

Smoldering

A result of incomplete combustion Major constituents

Particulate matter Solid or liquid particle suspended in

atmosphere Condensed hydrocarbons and tar

materials Entrained fragments of vegetation and

ash CO2 and CO H2O Gaseous hydrocarbons

Smokevolume burned increases for Low intensity fires in moist or living

fuels High rates of spread (amp less efficient

combustion)

CO CO2

GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains

Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to

fuel surface only

Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions

Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel

surface onlysurface only

Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions

Convection Vertical (or other direction)

movement of gas or liquid as heat rises

Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven

Carries firebrands away from fire spotting potential

Can create enormous columns and drive fire behavior

ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of

gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires

and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven

Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential

Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior

Heat Transfer ProcessesHeat Transfer Processes

ConductionConduction Transfer by molecular activity Transfer by molecular activity

withinwithin a solid object a solid object Primary method for raising Primary method for raising

temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels

that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels

requiring additional heat to reach requiring additional heat to reach ignitionignition

Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)

Residency Time Duration for flaming combustion to pass a specific location

Flame Length amp Depth

Residency Time = Flame DepthROS

Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-

1)

I = hwr

I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread

Flame Length is a good estimate of intensity

Severity Impact of fire on the environment Plants animals soils water

SE

VE

RIT

Y

INTENSITY

LOW

HIGH

HIGHLOW

Backing fire in long unburned longleaf pine

Stand replacing fire in mixed conifer forests

Head fire in frequently burned longleaf pine

Chaparral Brush Fires

1 Weather

2 Fuels 3 Topography

Surface Fuels Grasses Shrubs Litter (leaves)

Woody debris

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Fuel Oxygen

Heat

The Fire TriangleThe Fire Triangle

Energy release in the form of heat and light when oxygen combines Energy release in the form of heat and light when oxygen combines with a combustible material (fuel) at a suitably high temperaturewith a combustible material (fuel) at a suitably high temperature

Photosynthesis converts radiant energy to stored chemical energy (CO2 + H2O ---light-----gt C6H12O6 + O2)

Combustion reverses photosynthesis(C6H12O6 + O2 ---high temperature-----gt H2O + CO2 + heat and light)

(fuel) (325 C for wood)

Same process as decay and decomposition Begins with endothermic reaction becomes exothermic Produces thermal radiant and kinetic energy

Extinction insufficient heat to sustain combustion

HEAT

WATER ampORGANICGASES

Pre-Ignition

VISIBLE SMOKE

Smoldering

CO CO2

Glowing

2CO WATER

VISIBLE SMOKE

Flaming

4 Phases of Combustion

Pre-ignition Requires heatenergy input to

increase surface temperature gt200˚C

Dehydration Volatilization of waxes oils other

extractives Pyrolysis (chemical decomposition of

organic matter without Oxygenndash inside fuels emits volatiles)

Volatiles either condense into particles (smoke) or are consumed during flaming combustion

HEAT

WATER ampORGANICGASES

Pre-Ignition

Ignition Transition to flaming

combustion gases released by pyrolysis ignite

Surface temperatures around 320 C (600F)

Heat released by combustion brings other fuels to ignition

Flaming combustion Surface temperatures 200- 500˚

C Combustible volatiles ignite

above surface creating flame the GASES are burning not the fuel itself

Combustion occurs in zone above fuel surface

Oxidation produces heat CO2 H2O and incompletely degraded organic compounds

Smoke includes these + other gases which condense or reform above flame zone

2CO WATER

VISIBLE SMOKE

Flaming

Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas

production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other

compounds Smoldering duff and ground fires raise

soil temperature and can kill roots Large quantities of smoke

VISIBLE SMOKE

Smoldering

A result of incomplete combustion Major constituents

Particulate matter Solid or liquid particle suspended in

atmosphere Condensed hydrocarbons and tar

materials Entrained fragments of vegetation and

ash CO2 and CO H2O Gaseous hydrocarbons

Smokevolume burned increases for Low intensity fires in moist or living

fuels High rates of spread (amp less efficient

combustion)

CO CO2

GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains

Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to

fuel surface only

Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions

Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel

surface onlysurface only

Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions

Convection Vertical (or other direction)

movement of gas or liquid as heat rises

Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven

Carries firebrands away from fire spotting potential

Can create enormous columns and drive fire behavior

ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of

gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires

and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven

Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential

Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior

Heat Transfer ProcessesHeat Transfer Processes

ConductionConduction Transfer by molecular activity Transfer by molecular activity

withinwithin a solid object a solid object Primary method for raising Primary method for raising

temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels

that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels

requiring additional heat to reach requiring additional heat to reach ignitionignition

Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)

Residency Time Duration for flaming combustion to pass a specific location

Flame Length amp Depth

Residency Time = Flame DepthROS

Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-

1)

I = hwr

I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread

Flame Length is a good estimate of intensity

Severity Impact of fire on the environment Plants animals soils water

SE

VE

RIT

Y

INTENSITY

LOW

HIGH

HIGHLOW

Backing fire in long unburned longleaf pine

Stand replacing fire in mixed conifer forests

Head fire in frequently burned longleaf pine

Chaparral Brush Fires

1 Weather

2 Fuels 3 Topography

Surface Fuels Grasses Shrubs Litter (leaves)

Woody debris

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Photosynthesis converts radiant energy to stored chemical energy (CO2 + H2O ---light-----gt C6H12O6 + O2)

Combustion reverses photosynthesis(C6H12O6 + O2 ---high temperature-----gt H2O + CO2 + heat and light)

(fuel) (325 C for wood)

Same process as decay and decomposition Begins with endothermic reaction becomes exothermic Produces thermal radiant and kinetic energy

Extinction insufficient heat to sustain combustion

HEAT

WATER ampORGANICGASES

Pre-Ignition

VISIBLE SMOKE

Smoldering

CO CO2

Glowing

2CO WATER

VISIBLE SMOKE

Flaming

4 Phases of Combustion

Pre-ignition Requires heatenergy input to

increase surface temperature gt200˚C

Dehydration Volatilization of waxes oils other

extractives Pyrolysis (chemical decomposition of

organic matter without Oxygenndash inside fuels emits volatiles)

Volatiles either condense into particles (smoke) or are consumed during flaming combustion

HEAT

WATER ampORGANICGASES

Pre-Ignition

Ignition Transition to flaming

combustion gases released by pyrolysis ignite

Surface temperatures around 320 C (600F)

Heat released by combustion brings other fuels to ignition

Flaming combustion Surface temperatures 200- 500˚

C Combustible volatiles ignite

above surface creating flame the GASES are burning not the fuel itself

Combustion occurs in zone above fuel surface

Oxidation produces heat CO2 H2O and incompletely degraded organic compounds

Smoke includes these + other gases which condense or reform above flame zone

2CO WATER

VISIBLE SMOKE

Flaming

Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas

production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other

compounds Smoldering duff and ground fires raise

soil temperature and can kill roots Large quantities of smoke

VISIBLE SMOKE

Smoldering

A result of incomplete combustion Major constituents

Particulate matter Solid or liquid particle suspended in

atmosphere Condensed hydrocarbons and tar

materials Entrained fragments of vegetation and

ash CO2 and CO H2O Gaseous hydrocarbons

Smokevolume burned increases for Low intensity fires in moist or living

fuels High rates of spread (amp less efficient

combustion)

CO CO2

GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains

Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to

fuel surface only

Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions

Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel

surface onlysurface only

Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions

Convection Vertical (or other direction)

movement of gas or liquid as heat rises

Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven

Carries firebrands away from fire spotting potential

Can create enormous columns and drive fire behavior

ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of

gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires

and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven

Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential

Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior

Heat Transfer ProcessesHeat Transfer Processes

ConductionConduction Transfer by molecular activity Transfer by molecular activity

withinwithin a solid object a solid object Primary method for raising Primary method for raising

temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels

that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels

requiring additional heat to reach requiring additional heat to reach ignitionignition

Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)

Residency Time Duration for flaming combustion to pass a specific location

Flame Length amp Depth

Residency Time = Flame DepthROS

Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-

1)

I = hwr

I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread

Flame Length is a good estimate of intensity

Severity Impact of fire on the environment Plants animals soils water

SE

VE

RIT

Y

INTENSITY

LOW

HIGH

HIGHLOW

Backing fire in long unburned longleaf pine

Stand replacing fire in mixed conifer forests

Head fire in frequently burned longleaf pine

Chaparral Brush Fires

1 Weather

2 Fuels 3 Topography

Surface Fuels Grasses Shrubs Litter (leaves)

Woody debris

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

HEAT

WATER ampORGANICGASES

Pre-Ignition

VISIBLE SMOKE

Smoldering

CO CO2

Glowing

2CO WATER

VISIBLE SMOKE

Flaming

4 Phases of Combustion

Pre-ignition Requires heatenergy input to

increase surface temperature gt200˚C

Dehydration Volatilization of waxes oils other

extractives Pyrolysis (chemical decomposition of

organic matter without Oxygenndash inside fuels emits volatiles)

Volatiles either condense into particles (smoke) or are consumed during flaming combustion

HEAT

WATER ampORGANICGASES

Pre-Ignition

Ignition Transition to flaming

combustion gases released by pyrolysis ignite

Surface temperatures around 320 C (600F)

Heat released by combustion brings other fuels to ignition

Flaming combustion Surface temperatures 200- 500˚

C Combustible volatiles ignite

above surface creating flame the GASES are burning not the fuel itself

Combustion occurs in zone above fuel surface

Oxidation produces heat CO2 H2O and incompletely degraded organic compounds

Smoke includes these + other gases which condense or reform above flame zone

2CO WATER

VISIBLE SMOKE

Flaming

Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas

production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other

compounds Smoldering duff and ground fires raise

soil temperature and can kill roots Large quantities of smoke

VISIBLE SMOKE

Smoldering

A result of incomplete combustion Major constituents

Particulate matter Solid or liquid particle suspended in

atmosphere Condensed hydrocarbons and tar

materials Entrained fragments of vegetation and

ash CO2 and CO H2O Gaseous hydrocarbons

Smokevolume burned increases for Low intensity fires in moist or living

fuels High rates of spread (amp less efficient

combustion)

CO CO2

GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains

Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to

fuel surface only

Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions

Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel

surface onlysurface only

Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions

Convection Vertical (or other direction)

movement of gas or liquid as heat rises

Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven

Carries firebrands away from fire spotting potential

Can create enormous columns and drive fire behavior

ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of

gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires

and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven

Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential

Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior

Heat Transfer ProcessesHeat Transfer Processes

ConductionConduction Transfer by molecular activity Transfer by molecular activity

withinwithin a solid object a solid object Primary method for raising Primary method for raising

temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels

that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels

requiring additional heat to reach requiring additional heat to reach ignitionignition

Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)

Residency Time Duration for flaming combustion to pass a specific location

Flame Length amp Depth

Residency Time = Flame DepthROS

Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-

1)

I = hwr

I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread

Flame Length is a good estimate of intensity

Severity Impact of fire on the environment Plants animals soils water

SE

VE

RIT

Y

INTENSITY

LOW

HIGH

HIGHLOW

Backing fire in long unburned longleaf pine

Stand replacing fire in mixed conifer forests

Head fire in frequently burned longleaf pine

Chaparral Brush Fires

1 Weather

2 Fuels 3 Topography

Surface Fuels Grasses Shrubs Litter (leaves)

Woody debris

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Pre-ignition Requires heatenergy input to

increase surface temperature gt200˚C

Dehydration Volatilization of waxes oils other

extractives Pyrolysis (chemical decomposition of

organic matter without Oxygenndash inside fuels emits volatiles)

Volatiles either condense into particles (smoke) or are consumed during flaming combustion

HEAT

WATER ampORGANICGASES

Pre-Ignition

Ignition Transition to flaming

combustion gases released by pyrolysis ignite

Surface temperatures around 320 C (600F)

Heat released by combustion brings other fuels to ignition

Flaming combustion Surface temperatures 200- 500˚

C Combustible volatiles ignite

above surface creating flame the GASES are burning not the fuel itself

Combustion occurs in zone above fuel surface

Oxidation produces heat CO2 H2O and incompletely degraded organic compounds

Smoke includes these + other gases which condense or reform above flame zone

2CO WATER

VISIBLE SMOKE

Flaming

Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas

production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other

compounds Smoldering duff and ground fires raise

soil temperature and can kill roots Large quantities of smoke

VISIBLE SMOKE

Smoldering

A result of incomplete combustion Major constituents

Particulate matter Solid or liquid particle suspended in

atmosphere Condensed hydrocarbons and tar

materials Entrained fragments of vegetation and

ash CO2 and CO H2O Gaseous hydrocarbons

Smokevolume burned increases for Low intensity fires in moist or living

fuels High rates of spread (amp less efficient

combustion)

CO CO2

GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains

Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to

fuel surface only

Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions

Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel

surface onlysurface only

Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions

Convection Vertical (or other direction)

movement of gas or liquid as heat rises

Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven

Carries firebrands away from fire spotting potential

Can create enormous columns and drive fire behavior

ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of

gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires

and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven

Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential

Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior

Heat Transfer ProcessesHeat Transfer Processes

ConductionConduction Transfer by molecular activity Transfer by molecular activity

withinwithin a solid object a solid object Primary method for raising Primary method for raising

temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels

that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels

requiring additional heat to reach requiring additional heat to reach ignitionignition

Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)

Residency Time Duration for flaming combustion to pass a specific location

Flame Length amp Depth

Residency Time = Flame DepthROS

Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-

1)

I = hwr

I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread

Flame Length is a good estimate of intensity

Severity Impact of fire on the environment Plants animals soils water

SE

VE

RIT

Y

INTENSITY

LOW

HIGH

HIGHLOW

Backing fire in long unburned longleaf pine

Stand replacing fire in mixed conifer forests

Head fire in frequently burned longleaf pine

Chaparral Brush Fires

1 Weather

2 Fuels 3 Topography

Surface Fuels Grasses Shrubs Litter (leaves)

Woody debris

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Ignition Transition to flaming

combustion gases released by pyrolysis ignite

Surface temperatures around 320 C (600F)

Heat released by combustion brings other fuels to ignition

Flaming combustion Surface temperatures 200- 500˚

C Combustible volatiles ignite

above surface creating flame the GASES are burning not the fuel itself

Combustion occurs in zone above fuel surface

Oxidation produces heat CO2 H2O and incompletely degraded organic compounds

Smoke includes these + other gases which condense or reform above flame zone

2CO WATER

VISIBLE SMOKE

Flaming

Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas

production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other

compounds Smoldering duff and ground fires raise

soil temperature and can kill roots Large quantities of smoke

VISIBLE SMOKE

Smoldering

A result of incomplete combustion Major constituents

Particulate matter Solid or liquid particle suspended in

atmosphere Condensed hydrocarbons and tar

materials Entrained fragments of vegetation and

ash CO2 and CO H2O Gaseous hydrocarbons

Smokevolume burned increases for Low intensity fires in moist or living

fuels High rates of spread (amp less efficient

combustion)

CO CO2

GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains

Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to

fuel surface only

Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions

Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel

surface onlysurface only

Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions

Convection Vertical (or other direction)

movement of gas or liquid as heat rises

Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven

Carries firebrands away from fire spotting potential

Can create enormous columns and drive fire behavior

ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of

gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires

and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven

Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential

Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior

Heat Transfer ProcessesHeat Transfer Processes

ConductionConduction Transfer by molecular activity Transfer by molecular activity

withinwithin a solid object a solid object Primary method for raising Primary method for raising

temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels

that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels

requiring additional heat to reach requiring additional heat to reach ignitionignition

Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)

Residency Time Duration for flaming combustion to pass a specific location

Flame Length amp Depth

Residency Time = Flame DepthROS

Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-

1)

I = hwr

I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread

Flame Length is a good estimate of intensity

Severity Impact of fire on the environment Plants animals soils water

SE

VE

RIT

Y

INTENSITY

LOW

HIGH

HIGHLOW

Backing fire in long unburned longleaf pine

Stand replacing fire in mixed conifer forests

Head fire in frequently burned longleaf pine

Chaparral Brush Fires

1 Weather

2 Fuels 3 Topography

Surface Fuels Grasses Shrubs Litter (leaves)

Woody debris

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Flaming combustion Surface temperatures 200- 500˚

C Combustible volatiles ignite

above surface creating flame the GASES are burning not the fuel itself

Combustion occurs in zone above fuel surface

Oxidation produces heat CO2 H2O and incompletely degraded organic compounds

Smoke includes these + other gases which condense or reform above flame zone

2CO WATER

VISIBLE SMOKE

Flaming

Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas

production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other

compounds Smoldering duff and ground fires raise

soil temperature and can kill roots Large quantities of smoke

VISIBLE SMOKE

Smoldering

A result of incomplete combustion Major constituents

Particulate matter Solid or liquid particle suspended in

atmosphere Condensed hydrocarbons and tar

materials Entrained fragments of vegetation and

ash CO2 and CO H2O Gaseous hydrocarbons

Smokevolume burned increases for Low intensity fires in moist or living

fuels High rates of spread (amp less efficient

combustion)

CO CO2

GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains

Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to

fuel surface only

Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions

Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel

surface onlysurface only

Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions

Convection Vertical (or other direction)

movement of gas or liquid as heat rises

Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven

Carries firebrands away from fire spotting potential

Can create enormous columns and drive fire behavior

ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of

gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires

and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven

Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential

Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior

Heat Transfer ProcessesHeat Transfer Processes

ConductionConduction Transfer by molecular activity Transfer by molecular activity

withinwithin a solid object a solid object Primary method for raising Primary method for raising

temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels

that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels

requiring additional heat to reach requiring additional heat to reach ignitionignition

Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)

Residency Time Duration for flaming combustion to pass a specific location

Flame Length amp Depth

Residency Time = Flame DepthROS

Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-

1)

I = hwr

I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread

Flame Length is a good estimate of intensity

Severity Impact of fire on the environment Plants animals soils water

SE

VE

RIT

Y

INTENSITY

LOW

HIGH

HIGHLOW

Backing fire in long unburned longleaf pine

Stand replacing fire in mixed conifer forests

Head fire in frequently burned longleaf pine

Chaparral Brush Fires

1 Weather

2 Fuels 3 Topography

Surface Fuels Grasses Shrubs Litter (leaves)

Woody debris

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Smoldering No visible flames Surface temperatures lt 500 C Carbon buildup on surface reduces gas

production that would maintain flame Occurs when fuels tightly packed Surface char oxidizes to CO2 H2O ash Continued oxidation of other

compounds Smoldering duff and ground fires raise

soil temperature and can kill roots Large quantities of smoke

VISIBLE SMOKE

Smoldering

A result of incomplete combustion Major constituents

Particulate matter Solid or liquid particle suspended in

atmosphere Condensed hydrocarbons and tar

materials Entrained fragments of vegetation and

ash CO2 and CO H2O Gaseous hydrocarbons

Smokevolume burned increases for Low intensity fires in moist or living

fuels High rates of spread (amp less efficient

combustion)

CO CO2

GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains

Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to

fuel surface only

Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions

Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel

surface onlysurface only

Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions

Convection Vertical (or other direction)

movement of gas or liquid as heat rises

Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven

Carries firebrands away from fire spotting potential

Can create enormous columns and drive fire behavior

ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of

gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires

and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven

Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential

Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior

Heat Transfer ProcessesHeat Transfer Processes

ConductionConduction Transfer by molecular activity Transfer by molecular activity

withinwithin a solid object a solid object Primary method for raising Primary method for raising

temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels

that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels

requiring additional heat to reach requiring additional heat to reach ignitionignition

Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)

Residency Time Duration for flaming combustion to pass a specific location

Flame Length amp Depth

Residency Time = Flame DepthROS

Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-

1)

I = hwr

I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread

Flame Length is a good estimate of intensity

Severity Impact of fire on the environment Plants animals soils water

SE

VE

RIT

Y

INTENSITY

LOW

HIGH

HIGHLOW

Backing fire in long unburned longleaf pine

Stand replacing fire in mixed conifer forests

Head fire in frequently burned longleaf pine

Chaparral Brush Fires

1 Weather

2 Fuels 3 Topography

Surface Fuels Grasses Shrubs Litter (leaves)

Woody debris

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

A result of incomplete combustion Major constituents

Particulate matter Solid or liquid particle suspended in

atmosphere Condensed hydrocarbons and tar

materials Entrained fragments of vegetation and

ash CO2 and CO H2O Gaseous hydrocarbons

Smokevolume burned increases for Low intensity fires in moist or living

fuels High rates of spread (amp less efficient

combustion)

CO CO2

GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains

Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to

fuel surface only

Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions

Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel

surface onlysurface only

Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions

Convection Vertical (or other direction)

movement of gas or liquid as heat rises

Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven

Carries firebrands away from fire spotting potential

Can create enormous columns and drive fire behavior

ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of

gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires

and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven

Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential

Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior

Heat Transfer ProcessesHeat Transfer Processes

ConductionConduction Transfer by molecular activity Transfer by molecular activity

withinwithin a solid object a solid object Primary method for raising Primary method for raising

temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels

that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels

requiring additional heat to reach requiring additional heat to reach ignitionignition

Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)

Residency Time Duration for flaming combustion to pass a specific location

Flame Length amp Depth

Residency Time = Flame DepthROS

Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-

1)

I = hwr

I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread

Flame Length is a good estimate of intensity

Severity Impact of fire on the environment Plants animals soils water

SE

VE

RIT

Y

INTENSITY

LOW

HIGH

HIGHLOW

Backing fire in long unburned longleaf pine

Stand replacing fire in mixed conifer forests

Head fire in frequently burned longleaf pine

Chaparral Brush Fires

1 Weather

2 Fuels 3 Topography

Surface Fuels Grasses Shrubs Litter (leaves)

Woody debris

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

CO CO2

GlowingbullAll volatiles have already been driven off oxygen reaches the combustion surfaces and there is no visible smoke (products are CO2 and CO)bullOxidation of solid fuel accompanied by incandescencebullThis phase follows smoldering combustion continues until temperature drops or only non-combustible ash remains

Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to

fuel surface only

Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions

Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel

surface onlysurface only

Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions

Convection Vertical (or other direction)

movement of gas or liquid as heat rises

Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven

Carries firebrands away from fire spotting potential

Can create enormous columns and drive fire behavior

ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of

gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires

and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven

Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential

Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior

Heat Transfer ProcessesHeat Transfer Processes

ConductionConduction Transfer by molecular activity Transfer by molecular activity

withinwithin a solid object a solid object Primary method for raising Primary method for raising

temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels

that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels

requiring additional heat to reach requiring additional heat to reach ignitionignition

Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)

Residency Time Duration for flaming combustion to pass a specific location

Flame Length amp Depth

Residency Time = Flame DepthROS

Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-

1)

I = hwr

I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread

Flame Length is a good estimate of intensity

Severity Impact of fire on the environment Plants animals soils water

SE

VE

RIT

Y

INTENSITY

LOW

HIGH

HIGHLOW

Backing fire in long unburned longleaf pine

Stand replacing fire in mixed conifer forests

Head fire in frequently burned longleaf pine

Chaparral Brush Fires

1 Weather

2 Fuels 3 Topography

Surface Fuels Grasses Shrubs Litter (leaves)

Woody debris

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Radiation For example the sun and your handhellip Electromagnetic waves transfer heat to

fuel surface only

Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directions

Radiation For example the sun and your handhellipFor example the sun and your handhellip Electromagnetic waves transfer heat to fuel Electromagnetic waves transfer heat to fuel

surface onlysurface only

Accounts for most drying and heating of Accounts for most drying and heating of fuel surfaces ahead of flame or on opposite fuel surfaces ahead of flame or on opposite steep slopesndash radiates in all directionssteep slopesndash radiates in all directions

Convection Vertical (or other direction)

movement of gas or liquid as heat rises

Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven

Carries firebrands away from fire spotting potential

Can create enormous columns and drive fire behavior

ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of

gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires

and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven

Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential

Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior

Heat Transfer ProcessesHeat Transfer Processes

ConductionConduction Transfer by molecular activity Transfer by molecular activity

withinwithin a solid object a solid object Primary method for raising Primary method for raising

temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels

that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels

requiring additional heat to reach requiring additional heat to reach ignitionignition

Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)

Residency Time Duration for flaming combustion to pass a specific location

Flame Length amp Depth

Residency Time = Flame DepthROS

Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-

1)

I = hwr

I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread

Flame Length is a good estimate of intensity

Severity Impact of fire on the environment Plants animals soils water

SE

VE

RIT

Y

INTENSITY

LOW

HIGH

HIGHLOW

Backing fire in long unburned longleaf pine

Stand replacing fire in mixed conifer forests

Head fire in frequently burned longleaf pine

Chaparral Brush Fires

1 Weather

2 Fuels 3 Topography

Surface Fuels Grasses Shrubs Litter (leaves)

Woody debris

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Convection Vertical (or other direction)

movement of gas or liquid as heat rises

Heats plant foliage above surface fires and fuels ahead of the flame on steep slopes or if wind driven

Carries firebrands away from fire spotting potential

Can create enormous columns and drive fire behavior

ConvectionConvection Vertical (or other direction) movement of Vertical (or other direction) movement of

gas or liquid as heat risesgas or liquid as heat rises Heats plant foliage above surface fires Heats plant foliage above surface fires

and fuels ahead of the flame on steep and fuels ahead of the flame on steep slopes or if wind drivenslopes or if wind driven

Carries firebrands away from fire Carries firebrands away from fire spotting potentialspotting potential

Can create enormous columns and drive Can create enormous columns and drive fire behaviorfire behavior

Heat Transfer ProcessesHeat Transfer Processes

ConductionConduction Transfer by molecular activity Transfer by molecular activity

withinwithin a solid object a solid object Primary method for raising Primary method for raising

temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels

that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels

requiring additional heat to reach requiring additional heat to reach ignitionignition

Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)

Residency Time Duration for flaming combustion to pass a specific location

Flame Length amp Depth

Residency Time = Flame DepthROS

Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-

1)

I = hwr

I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread

Flame Length is a good estimate of intensity

Severity Impact of fire on the environment Plants animals soils water

SE

VE

RIT

Y

INTENSITY

LOW

HIGH

HIGHLOW

Backing fire in long unburned longleaf pine

Stand replacing fire in mixed conifer forests

Head fire in frequently burned longleaf pine

Chaparral Brush Fires

1 Weather

2 Fuels 3 Topography

Surface Fuels Grasses Shrubs Litter (leaves)

Woody debris

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Heat Transfer ProcessesHeat Transfer Processes

ConductionConduction Transfer by molecular activity Transfer by molecular activity

withinwithin a solid object a solid object Primary method for raising Primary method for raising

temperatures within large fuelstemperatures within large fuels Occurs between objectsfuels Occurs between objectsfuels

that are in contactthat are in contact Transfers heat in dense fuels Transfers heat in dense fuels

requiring additional heat to reach requiring additional heat to reach ignitionignition

Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)

Residency Time Duration for flaming combustion to pass a specific location

Flame Length amp Depth

Residency Time = Flame DepthROS

Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-

1)

I = hwr

I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread

Flame Length is a good estimate of intensity

Severity Impact of fire on the environment Plants animals soils water

SE

VE

RIT

Y

INTENSITY

LOW

HIGH

HIGHLOW

Backing fire in long unburned longleaf pine

Stand replacing fire in mixed conifer forests

Head fire in frequently burned longleaf pine

Chaparral Brush Fires

1 Weather

2 Fuels 3 Topography

Surface Fuels Grasses Shrubs Litter (leaves)

Woody debris

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Rate of spread (ROS) rate at which fire front advances through forest fuel (ftsec chainsmin)

Residency Time Duration for flaming combustion to pass a specific location

Flame Length amp Depth

Residency Time = Flame DepthROS

Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-

1)

I = hwr

I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread

Flame Length is a good estimate of intensity

Severity Impact of fire on the environment Plants animals soils water

SE

VE

RIT

Y

INTENSITY

LOW

HIGH

HIGHLOW

Backing fire in long unburned longleaf pine

Stand replacing fire in mixed conifer forests

Head fire in frequently burned longleaf pine

Chaparral Brush Fires

1 Weather

2 Fuels 3 Topography

Surface Fuels Grasses Shrubs Litter (leaves)

Woody debris

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Intensity ndash rate of heat energy during combustion Reaction intensity per unit area (BTUft-2min-1) Fireline Intensity per unit length of the fire front (BTUft-1min-

1)

I = hwr

I fireline intensityh fuel heat contentw weight of fuel consumed per unit arear rate of spread

Flame Length is a good estimate of intensity

Severity Impact of fire on the environment Plants animals soils water

SE

VE

RIT

Y

INTENSITY

LOW

HIGH

HIGHLOW

Backing fire in long unburned longleaf pine

Stand replacing fire in mixed conifer forests

Head fire in frequently burned longleaf pine

Chaparral Brush Fires

1 Weather

2 Fuels 3 Topography

Surface Fuels Grasses Shrubs Litter (leaves)

Woody debris

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Severity Impact of fire on the environment Plants animals soils water

SE

VE

RIT

Y

INTENSITY

LOW

HIGH

HIGHLOW

Backing fire in long unburned longleaf pine

Stand replacing fire in mixed conifer forests

Head fire in frequently burned longleaf pine

Chaparral Brush Fires

1 Weather

2 Fuels 3 Topography

Surface Fuels Grasses Shrubs Litter (leaves)

Woody debris

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

1 Weather

2 Fuels 3 Topography

Surface Fuels Grasses Shrubs Litter (leaves)

Woody debris

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Surface Fuels Grasses Shrubs Litter (leaves)

Woody debris

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Ground Fuels Duff (partially

decomposed)

Peat Roots Stumps

mineral soil

litter

fermentation layerhumus

Duff

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Aerial Fuels Crown or canopy of

overstory

Ladder Fuels (located between crown and surface fuels)

Smaller trees Vines

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Size and Shape Surface areavolume

ratio Grasses Palmetto Branches Logs

10001

401

Particle Density

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Fuel Chemistry Volatile oils

Mineral Content Dampening effect on

combustion

Heat Content (stored energy)

6000-12000 BTUlb

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Fuel Arrangement Vertical Grasses amp shrubs

Horizontal Litter Downed woody debris

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Fuel Loading By size classes

Compactness Bulk density (fuel loadfuelbed volume)

Packing ratio (fuelbed densityparticle density)

Continuity Vertical Horizontal

ALL FUELBED PROPERTIES

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Fuel Moisture Content (FMC) Large dampening effect on

combustion Heat sink

FMC changes hourly daily and seasonally

Fuel Moisture Content () = (Water Weight Dry Fuel Weight) x 100

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

What influences FMC In Dead Fuels Precipitation (amount

and duration) Temperature Relative humidity Wind

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Equilibrium Moisture Content For a given temperature and RH dead fuel

will reach a FMC at equilibrium Environmental conditions are not constant Fuel is constantly changes FMC to reach

EMC

The lag time to reach EMC depends on particle size

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Timelag categories for dead woody fuels

Timelag Class Fuel Diameter

Timelag Range (hr)

1 Hour 0-14rdquo 0-2

10 Hour frac14rdquo-1rdquo 2-20

100 Hour 1-3rdquo 20-200

1000 Hour 3-8rdquo 200-2000

Timelag or ldquoresponse timerdquo is the time it takes for 63 of the change to occur between one EMC and a second EMC when a fuel in equilibrium with a stable environmental condition is suddenly exposed to a different stable environmental condition

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Small diameter fuels react quickly to hourly and daily changes Important to monitor

Large diameter fuels react more to seasonal changes California versus Florida

Fine fuels drive fire behavior

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Moisture of Extinction Dead 12-40 Live gt120

Available Fuel

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Florida Fine Fuel Moisture Calculation Chart

httpwwwfl-dofcomwildfirerx_traininghtmlcbc

Live Fuels FMC can be much higher than dead

fuels (100-300) Influenced by Drought (KBDI) RH Wind

Ignition of live fuels may largely depend the combustion characteristics of other fuels (eg dead surface fuels)

Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in

burning long unburned forests May smolder for long durations May cause lots of smoke

FMCWind

Increases O2 Bends flames Increases ROS Dries fuels

convectionwind

radiation

conduction

Slopes Similar effect as

wind Bends flames ROS higher

upslope

Slope Positiontop middle bottom

Aspect

Other topographic features Valleys Box Canyons Steep draws Elevation

ELEVATION

Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70

Fire Behavior Prediction Models (eg BehavePlus)

INPUTS OUTPUTSFuel characteristics Rate of

SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip

• Slide 9
• Slide 15
• Slide 46

Duff Moisture Very dry to very moist lt30 FMC duff can burn on its own Potential for tree mortality in

burning long unburned forests May smolder for long durations May cause lots of smoke

FMCWind

Increases O2 Bends flames Increases ROS Dries fuels

convectionwind

radiation

conduction

Slopes Similar effect as

wind Bends flames ROS higher

upslope

Slope Positiontop middle bottom

Aspect

Other topographic features Valleys Box Canyons Steep draws Elevation

ELEVATION

Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70

Fire Behavior Prediction Models (eg BehavePlus)

INPUTS OUTPUTSFuel characteristics Rate of

SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip

• Slide 9
• Slide 15
• Slide 46

FMCWind

Increases O2 Bends flames Increases ROS Dries fuels

convectionwind

radiation

conduction

Slopes Similar effect as

wind Bends flames ROS higher

upslope

Slope Positiontop middle bottom

Aspect

Other topographic features Valleys Box Canyons Steep draws Elevation

ELEVATION

Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70

Fire Behavior Prediction Models (eg BehavePlus)

INPUTS OUTPUTSFuel characteristics Rate of

SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip

• Slide 9
• Slide 15
• Slide 46

Slopes Similar effect as

wind Bends flames ROS higher

upslope

Slope Positiontop middle bottom

Aspect

Other topographic features Valleys Box Canyons Steep draws Elevation

ELEVATION

Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70

Fire Behavior Prediction Models (eg BehavePlus)

INPUTS OUTPUTSFuel characteristics Rate of

SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip

• Slide 9
• Slide 15
• Slide 46

Aspect

Other topographic features Valleys Box Canyons Steep draws Elevation

ELEVATION

Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70

Fire Behavior Prediction Models (eg BehavePlus)

INPUTS OUTPUTSFuel characteristics Rate of

SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip

• Slide 9
• Slide 15
• Slide 46

Other topographic features Valleys Box Canyons Steep draws Elevation

ELEVATION

Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70

Fire Behavior Prediction Models (eg BehavePlus)

INPUTS OUTPUTSFuel characteristics Rate of

SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip

• Slide 9
• Slide 15
• Slide 46

ELEVATION

Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70

Fire Behavior Prediction Models (eg BehavePlus)

INPUTS OUTPUTSFuel characteristics Rate of

SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip

• Slide 9
• Slide 15
• Slide 46

Indicators (on a Rx burn) KBDIgt500 FMC (fine) lt7 RHlt30 Cold front approaching Gusty winds Dust devilsfire whirls Just inland from seabreeze Well-defined convection column Thunderstorms Spotting DI approaching 70

Fire Behavior Prediction Models (eg BehavePlus)

INPUTS OUTPUTSFuel characteristics Rate of

SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip

• Slide 9
• Slide 15
• Slide 46

Fire Behavior Prediction Models (eg BehavePlus)

INPUTS OUTPUTSFuel characteristics Rate of

SpreadFMC Fireline IntensitySlope Flame LengthsWind and morehellip

• Slide 9
• Slide 15
• Slide 46

• Slide 9
• Slide 15
• Slide 46