Pg. 57

The discovery of controlling fire made it an early technology.

Examples of Fire use todayconstructive -used for our beneficdestructive -causing us grief

ADD Fire triangle

Fire is oxidation in action ..... combustion is the rapid reaction of oxygen and organic material

burning wood: produces carbon dioxide, water and heat

Pg. 57STAGES OF FIRE1. Preheating (starting the fire):

a) water removed from plant/organic material b) temperature of material increases – pyrolysis(chemical structure of wood breaks down yieldsflammable components)

2.) Flaming combustion stand back!!!burning=lots of energy released

3.) Glowing combustion – no flames but those embers are hot!

FIGURE LINK

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HOW DOES FIRE SPREAD?1) slowly along the ground

glowing combustion dominates

2) wall of fire - flaming combustion dominates

3) crown fire -fire in tree tops similar to wall of fire justin the tree trops

ADD Ladder Fuels -stepping up from one fuel level to the next.

ND pg. 407 Fig. 14.2

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WHAT HELPS THE SPREAD OF FIRE?1) Wind - pushes fire, feeds with oxygen

2) Fuel: Type of vegetation burning & how much Oils in wood (eucalyptus)

highly flammable (chaparral) vs. flame resistant

a.) Branches close to ground or not

b.) Lots of shrubby under storyRemember ladder fuels.

c.) Slash- brush piles left from clearing vegitation3) Moisture - wet or dry and for how long

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WHAT HELPS THE SPREAD OF FIRE?

4) Topography of land - hills - fire burns faster up slope - (convection =heat rises so preheats)-topography effects vegetation types

5) Positive feedback - fire creates unstable air and may create fire tornado-carry burning debris and start new fires.

Heat rises, sucks in oxygen from sides=more combustion-compare to in space to the make point

Positive Feedback is a “Vicious Cycle” but it is “positive”?

ADD pg. 58

HOW DO HOMES CATCH ON FIRE?

1.) Physical contact -Flames travels right to home

2.) Radiant heat causes home materials to ignite.warming your hands but be careful

*Flames do not have to touch the house.

3.) Firebrands- glowing embers blown by the wind tonew areas.

ADD pg. 58

WHAT TO DO….

1.) HOME DESIGNA.) set back from top of slope- 100 ft

minimum.ND pg. 420 fig. 14.25B.) building materials -flammable vs.

nonflammableC.) design- no overhanging decks/eavesD.) wide, easily accessible drivewaysE.) Roof- fire proof because of firebrandsND pg. 419 fig. 14.23

WHY?? on all

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WHAT TO DO….

1.) LANDSCAPINGA.) keep a 30’ barrier around homeB.) Keep trees trimmed (side and over roof)C.) use fire resistant plants -succulent ice

plantND pg. 421 fig. 14.26

D.) Keep surrounding forest thin-ladder fuels- remove ground level that could spread to crown

E.) keep slash -dead stuff cleared out. Results: ND pg. 418 fig. 14.22

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WHERE DO FIRES OCCUR?General Trend:Regions that experience wet and dry seasons (wet=plant growth dry=fire) Drought areas

Examples: 1.) Great Lakes 1871 clearing fields for ag. use = lots of wood debris left.

Long dry spell.

Strong winds.

Result - huge area burned farms and towns: Peshtigo, WI wall of flames moved fast 1100+ casualties

Pg. 592.) Chicago, IL-Oct. 8, 1871

Legend: Mrs. O’Leary’s cow kicked a lanternover = wind whipped flames - heart of the city burned, 300 casualties.

ADD1.) Unusually dry summer

2.) City had just finished building sidewalks out of wood

Pg. 593.) CALIFORNIA ( S.F. and S. Calif.) is a location

where fire is always a hazard certain times of year.

WHY?

a)vegetation type (chaparral - very flammable fire species - need fire to reseed)

b) hilly - fire races uphill- CONVECTIONc) homes built close to vegetation and on steep

hillsd) drought not uncommone) warm winds commonf) people/wacko in the woods - can start fires -

arsonist

ADD pg.59Baja vs. Southern CaliforniaSouthern California1.) Fires in the early, cooler, wetter season are put

out quickly-allows maximal plant growth.

2.) This leaves (not intended) lots of highly flammable chaparral to burn in the drier autumn.

3.) Fires are fought energetically and with lots of $a.) leaves behind dense overgrowths of

chaparral.b.) as chaparral grows it becomes more

flammable.

4.) Warm, dry winds occur in autumn when wehave lots of fuel

RESULTS: leaves lots of flammable fuel for the hot dry season

ADD pg.59Baja vs. Southern California

Baja

1.) Fires are NOT fought energetically and with little $

a.) leaves little overgrowth of chaparral.b.) as chaparral grows it becomes more

flammable.

SO…. We have less chaparral AND it is less flammable.

2.) Warm, dry winds occur in autumn BUT don’t have much fuel to feed fires.

RESULT: less fuel during the hot dry autumn.

ADD pg.59Baja vs. Southern CaliforniaTotal

Area *AreaBurned *

% Burned

% BurnedAfter Sept. 1

Number of Fires

S.C. 2,019 166 8.2 72 203

BAJA 1,202 95 7.9 20 488

* 1000’s hectares

ADD pg.59Baja vs. Southern California

Distribution:

1.) S.C. a few biggies-and burns higher %

2.) Baja a bunch of little ones

ND pg. 424 fig.14.28

*BIG QUESTION: Should we continue to fight big fires or let the early season fires go more?

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IF YOU LIVE IN A FIRE PRONE AREA WHAT CAN YOU DO?

1.) Build for fire

NO: Wood roof, wood house, wood deck,no. veg. near house

QUIZ

1.) Which of the following best describes the southernCalifornia case history (compared to Baja)

a.) let little fires burnb.) fight little firesc.) spend little money fighting fired.) results in a small amount of flammable material for

the hot dry season

2.) Why are fires a continual hazard in southern California?A) older vegetation resists burning B) moist conditions are common C) homes on hillsides D) cool moist winds are common

QUIZ

3.) Which of the following best represents the safest

course of action when designing landscapinga.) 50’ setback from top of slope and dense

underbrush b.) fire wood stored near the house and a 30’

barriersurrounding the house

c.) trimming overhanging trees and removing slash(debris)

d.) building on top of a hill and planning up to the house

4.) Which of the following is significant in aiding the spread of fires:

A) types of vegetation and topographyB) size of house and building materialC) number of rivers in area and moistureD) how many lakes there are in an area and fuel

QUIZ

5.) What best describes how convection causes burningA) Heat rises and fire burns up hillB) Heat rises and fire burns down hillC) Heat sinks and fire burns up hillD) Heat sinks and fire burns down hill

6.) What best describes how radiation causes burning?A)The fire has to physically touch the side of the houseB) The heat of the fire has to rise uphill to the houseC) Firebrands drift onto new areas causing new small firesD) The flames give off energy that begins to warm things

around it without touching them

QUIZ

7.) What best describes the conditions in theGreat Lakes region in 1871

A) Dry, high winds, high topographyB) Dry, low winds, high topographyC) Dry, high winds, low topographyD) Dry, low winds, low topography

8.) Which of the following best describes a fires positivefeedback behavior?

A) a fire burning down hill causing less burningB) A fire sends out firebrands causing the fire to get

bigger and biggerC) moist air causing less burningD) a fire running out of fuel

QUIZ

9) What contributed to the Chicago fires of 1871?

A) wooden sidewalks, dry conditions, and a cowB) wooden sidewalks, moist conditions, and a cowC) stone sidewalks, dry conditions, and an ostrichD) wooden sidewalks, dry conditions, and an ostrich