hydrologic cycle

7/21/2019 Hydrologic Cycle

http://slidepdf.com/reader/full/hydrologic-cycle-56e028cd426c2 1/41

Climate and Global Change Notes

23-1

Hydrologic Cycle

Surface-Atmosphere Exchange of Water

Water Cycle

Science Concepts

EvaporationCondensationPrecipitationRunoff




23-2

Hydrologic Cycle

Change in Annual Precipitation




23-3

Hydrologic Cycle

Modeled Environmental Water Scarcity Index• Scarcity is where the amount of water removed from the system puts theecosystem at risk by tapping into the environmental water demand, i.e., theamount of water needed to sustain the integrity of the ecosystem

• Areas above 0.4 are under ecosystem environmental stress• Areas higher than 0.8 (orange and red) are highly-stressed environmentally

http://www.iucn.org/themes/wani/eatlas/html/gm16.html




23-4

Hydrologic Cycle

The Water Cycle• All streamsflow into thesea, yet thesea is neverfull.

To the placethe streamscome from,there theyreturn again.

Ecclesiastes

1:7 (NewInternationalVersion)

http://ga.water.usgs.gov/edu/watercycle.html




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TheWaterCycle

Hydrologic Cycle

425

Evaporation

71

Evapotranspiration

111

Precipitation

385

Precipitation

40

Vapor Transport

Surface

Runoff

Groundwater FlowPercolation40

Return Flow 1012 m3 per year




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Hydrologic Cycle

GOES Waterapor Image


http://slidepdf.com/reader/full/hydrologic-cycle-56e028cd426c2 7/41Climate and Global Change Notes

23-7

Hydrologic Cycle

GOES i!i"leImage



23-8

Hydrologic Cycle

Mean Glo"al Precipita"le Water #cm$•• Annual AverageAnnual Average

http://isccp.giss.nasa.gov/cgi-bin/browsed2



23-9

Hydrologic Cycle

Mean Glo"alPrecipita"le Water #cm$#Con%t$

•• Seasonal variabilitySeasonal variability

S.W. Seemann, J. Li, W.P. Menzel – Univ. Wisconsin, NOAAS.W. Seemann, J. Li, W.P. Menzel – Univ. Wisconsin, NOAA



23-10

Hydrologic Cycle

Ama&on Sea!onal aria"ility•• Note seasonal rainfall variabilityNote seasonal rainfall variability

•• Amazon and Tropical seasons revolveAmazon and Tropical seasons revolve

around wet/dry not hot/coldaround wet/dry not hot/cold

http://earthobservatory.nasa.gov/Study/AmazonLAI/

QuickTime™ and a TIFF (Uncompressed) decompressor

are needed to see this picture.



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Hydrologic Cycle

Honolulu WSO Airport

• 21° 20’ N, 157° 55’ W

• Elevation = 10 ft

• Averages for10/1/49-3/31/05

Dec

i i

Dec



Ave. Max. Temp. = 84.0°F

Ave. Min. Temp. = 70.2°F

Ave. AnnualPrecipitation = 20.75 in

http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?hihono



23-12

Hydrologic Cycle

Mean 'anuary Moi!tureDewpoint Temperature (°F)1961-1990

Relative Humidity (%)1961-1990

http://www.nndc.noaa.gov/cgi-bin/climaps/climaps.pl



23-13

Hydrologic Cycle

Mean 'uly Moi!tureDewpoint Temperature (°F)1961-1990


Relative Humidity (%)1961-1990



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Hydrologic Cycle

Average (e)point Temperature #*+$ #,-./0,--/$


January July

Annual



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Hydrologic Cycle

'uly (e)point Temperature 1 (iurnalTemperature 2ange #*+$


Dewpoint Temperature Diurnal Temperature

Range



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Hydrologic Cycle

Average 2elative Humidity #,-./0,--/$


January July

Annual



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Hydrologic Cycle

Average Annual Precipitation #,-.,0,--/$• Annual

http://www.meted.ucar.edu/

broadcastmet/watershed/media/graphics/unit_6/nat_atlas_precip.jpg



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Hydrologic Cycle

Surface-Atmosphere Exchange of Water (Con’t)

Saturation ProcessesIncrease VaporCooling

LiftingMixingRadiational Cooling

Condensation TypesDew/FrostFog

HazeCloud Droplets

Science Concepts

Dry Adiabatic & Moist AdiabaticProcess

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23-19

Cloud! and Precipitation

Atmo!pheric Saturation Proce!!e!• Add moisture - Infrequent (Steam Fog)

• Cool to dewpoint temperature - Usual process

- Lifting

- Mixing

- Radiation

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23-20


Cloud +ormation• Condensation process

- Condensation nuclei

> What are they?

‡ Sea salt‡ Combustion products - smoke‡ Dust - Clay from plowed fields

> What is their distribution?

‡ Decrease with height - For Example: 0.1 as many at 3,000 ft as

at surface; 0.01 as many at 14,000 ft as at surface‡ More over cities than country‡ More over land than ocean - More giant nuclei over oceans

- Hygroscopic nuclei - Begin to attract water vapor at RHs as low as 70%

> What are they?

‡ Sea salt - Most common

Science quotes of 5th and6th graders -

I am not sure how cloudsget formed. But the cloudsknow how to do it, and thatis the important thing.

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23-21

Type! o3 Conden!ate• Dew

- Caused by radiational cooling of a surface to thedewpoint temperature of

the air

- Typical conditions

> Clear skies> Calm winds (little mixing)

> Nighttime

- Dewpoint temperature above 32°F


Science quotes of5th and 6thgraders -

Dew is formed onleaves when thesun shines down

on them andmakes themperspire.

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23-22


Type! o3 Conden!ate #Con%t$• Frost

- Caused by radiational cooling of a surface to the dewpoint temperature ofthe air

- Typical conditions> Clear skies> Calm winds (little mixing)> Nighttime

- Dewpoint temperature below 32°F

4uote“Teg weather report on the car radio had predicted a low of 35 degrees, and Pittmenbelieved it, seeing frost come out of his mouth.”David Morrell, "Desperate Measures" (p. 295)

What is wrong with this statement?

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Type! o3 Conden!ate #Con%t$• Fog

- Defined as a cloud on the ground

- Caused by

> Cooling of the air to itsdewpoint temperature

‡ Most common cause‡ Types of “cooling fog”

◊ Radiation fog◊ Advection fog◊ Upslope fog

> Evaporation of enough water to saturate the atmosphere

‡ Least frequent cause‡ Types of “evaporation fog”

◊ Steam fog◊ Warm-rain fog

- Dissipation (“burns-off”) by solar heating the surrounding ground; causes

mixing at edges-

In order to save the army during the

Revolutionary War Washington retreated fromLong Island overnight on Aug. 29, 1776. Bysunrise on the 30th not all the troops hadbeen ferried across the river to the NY side.However, a heavy fog had settled over theriver so they could continue to cross withoutbeing observed by the British troops and warships. Within an hour after the boats hadcarried the last of the 9,000 troops safelyacross, the wind shifted and the fogdispersed. Fog had helped save the army.1776, David McCullough, pp. 186-191

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23-24


2adiation andalley +og

Note contrails

Bright yellow is fog

Valley fog

AVHRR Satellite -4 November 1999 -Color enhanced (Visible,

near infrared (~1 micron),infrared (~3.7 micron)

AlabamaRivers

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Type! o3 Conden!ate #Con%t$• Haze

- Caused by particles (“large”) that scatter all wavelengths of light equally

- Increases as RH becomes greater than 70% because of hygroscopic nuclei

• Cloud droplets

- Cooling of the air aloft to its dewpoint temperature

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23-26

Hydrologic Cycle


Precipitation Physics (Con’t)Cloud Growth Processes

Droplet MultiplicationCascade Effect

Science Concepts

Surface TensionSolute EffectCurvature Effect

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2327


Cloud (roplet Gro)th Proce!!e!• Solute effect - Solution of water and nuclei material

- Helps droplet grow

- Decreases as droplet becomes larger

- Larger condensation nuclei, larger this effect. Thus,larger nuclei grow larger droplets

• Curvature effect - Caused by surface tension around droplet

- Hinders droplet grow

- Decreases as droplet becomes larger

Cloud (roplet Multiplication Proce!!

• Cascade effect - Large drops break into several smaller drops

Science quotes

of 5th and 6thgraders -

To most peoplesolutions meanfinding theanswers. But tochemistssolutions arethings that arestill all mixed up.

23-28




2328

Hydrologic Cycle


Precipitation Physics (Con’t)Rain Drop Formation

Collision and Coalescence Process

Bergeron Process

Precipitation Types

Science Concepts

Terminal VelocityGravitational ForceDrag Force

Pressure Gradient Force

Supercooled WaterSaturation Over Water Ice

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2329


+orce! on a +alling O"5ect• Terminal velocity ~120 mph

http://cyberbuzz.gatech.edu/skydive/photos/othermisc/ http://www.fcsurplus.ca/army/300745b.gif

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+orce! on a Cloud or 2ain (rop• Drag Force => Depends on square of Velocity and Shape of Drop

• Pressure Gradient Force => Depends on Volume of Drop

• Gravitational Force => Depends on the Mass of the Drop

Cloudor

Rain Drop

GravitationalForce

PressureGradientForce

DragForce

D = Cd ρ A V2 / 2

D =Drag forceCd =Drag coefficient

(usually determinedexperimentally)

ρ =Density of fluid (air)A =Reference area

(includes shape, etc.)V =Velocity

23-31





Atmo!pheric Particle!Name Diameter (cm) # per cm3 Large Ions 10-6 to 10-5 103 to 104

Smoke and Dust 10-5 to 10-4 variableLarge Condensation Nuclei 10-5 to 10-4 102

Giant Condensation Nuclei 10-4

to 10-2

1Cloud Droplets 10-4 to 10-2

Rain Drops 10-2 to 1

23-32





Particle Terminal elocitie!Particle Type Diameter (cm) m/s mphCondensation Nuclei 2 X 10-5 1 X 10-7 2 X 10-7

Small Cloud Droplets 1 X 10-5 3 X 10-3

Typical Cloud Droplets 2 X 10-3 1 X 10-2 2 X 10-2

Large Cloud Droplets 10-2 0.27 0.18

Small Rain Drops 0.1 4.0 8.9

Typical Rain Drops 0.2 6.5 14.6 Large Rain Drops 0.5 9.0 20.1

23-33





2aindrop Gro)th Proce!!• Raindrop 100 times larger diameter than cloud drop;1,000,000 time larger volume

• How does this tremendous growth occur?

- Coalescence process - “Warm” clouds

> Terminal velocity

‡ Gravitational force

‡ Pressure gradient force‡ Drag force

> Large drops fall faster than smaller drops

> Large drops collect smaller drops

Did you know -

Houses used to havethatched roofs - thickstraw, piled high, with nowood underneath. Because it was the aplace animals could getwarm, cats and othersmall animals (mice,bugs) lived in the roof.

When it rained, the thatch

became slippery andsometimes the animalswould slip off the roof.

Hence, the saying "It'sraining cats and dogs."

23-34





2aindrop Gro)th Proce!! #Con%t$• Raindrop 100 times larger diameter than cloud drop; 1,000,000 time largervolume (Con’t)

• How does this tremendous growth occur? (Con’t)

- Bergeron-Findeisen or ice process - “Cold” clouds

> Freezing nuclei

‡ Not enough in the atmosphere

‡ “Pure” water may not turn to ice until -40°C

> Between 0°C and -40°C, cloud is mixture of ice and liquid. Attemperatures below (i.e., heights above) -40°C, cloud is all ice.

> Ice crystals grow at expense of liquid drops

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Compari!on o3 Maritime and Continental 2ainCloud!

Maritime Continental

Number of Nuclei 940 cm-3 9500 cm-3

Droplet Concentration 50 cm-3 200 cm-3

Median Droplet Diameter 17 x 10-6 m 11 x 10-6 m

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Precipitation Cla!!i3ication• Drizzle

- Small, numerous drops falling out of fog or low layer stratus clouds- Indicative of stable stratification with little vertical motion

• Intermittent or Continuous Precipitation

- Rain or snow- Falling more or less evenly from altostratus or nimbostratus clouds- Caused by widespread and slow upward movement of large masses of air

• Showers (Squalls, Flurries)

- Precipitation with short duration with fair intervals- Caused by cumulus or cumulonimbus clouds, i.e, convection- Indicative of unstable stratification with fairly strong upward vertical

motion in localized regions

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Type! o3 Precipitation• Virgae

- Rain that evaporates below cloudbase, but before reaching the ground

• Rain

- Lower atmosphere above freezing- Drops large enough to fall relative to

air motions

http://www.ucar.edu/imagelibrary/1600-1650.html

http://www.wrh.noaa.gov/spokane/

042700/tstms.htm

23-38





Type! o3 Precipitation• Freezing Rain

- Ground at 0°C or colder- Very shallow layer of air near the ground

at near 0°C or colder

- Layer of air above this shallow layer attemperatures above 0°C

http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/cld/prcp/zr/frz.rxml

http://www.srh.noaa.gov/lzk/html/win121300.htm



23-39





Type! o3 Precipitation• Sleet, Grauple, Ice Pellets

- Clear ice “drops”- Precipitation is in the form of liquid

drops at sometime as it falls

- Deeper layer of air above the groundat 0°C or colder

- Layer of air above this deeper layer attemperatures above 0°C

http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/cld/prcp/slt.rxm

l



23-40







Type! o3 Precipitation #Con%t$• Snow- Opaque ice crystals or flakes- Crystals form at temperatures below 0°C

by the process of deposition

- No liquid phase- Ground at or near 0°C or colder- Layer of air above the ground at

temperatures below 0°C

http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/cld/prcp/snow.rxml

http://www.noaanews.noaa.gov/stories/s592b.htm

http://www.ucar.edu/imagelibrary/

1100-1133.html

Science quotes of 5th and 6th graders -

A blizzard is when it snows sideways.

23-41




Type! o3 Precipitation #Con%t$• Hail

- Large balls or lumps of ice- Often formed of concentric

rings of clearand opaque ice- Formed in clouds with strong

updrafts, i.e., convectiveclouds

http://www.eas.slu.edu/Photos/hail.html

http://www.ucar.edu/imagelibrary/1134-1166.html

Record Hail Stone - 7” diameter,18.75’’ circumference fell inAurora, NE, 22 June 2003

hydrologic cycle

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