Deserts & Eolian

Geomorphology

Ch 13

Kansas, 1977“Point Of Know Return”

CD Playing:

“Best of Kansas” Dust in the Wind

Aeolian Geomorphology

• Wind = Important Agent Where There Is Little Vegetation

• Deserts • Coastal Areas• Disturbed Lands, etc.• Mars, Venus, etc.

Why Is There Wind?

• Differences in Air Pressure.Why Are There Differences in Air Pressure?• Differences in Air Temperature.

– Hot Air Rises Because It Is Lighter.• Differences in Moisture Content.

– Which Is Heavier: Moist or Dry Air?

Which Is Heavier?Moist Air Dry Air

Which Is Heavier?

• Worse Yet, This May Get Scientific.

¡Excúseme, amigo! What Are the Principle Molecular

Components of Air?

Oxygen and Nitrogen! So What, Varmint?

Which Is Heavier?

• This May Get Scientific AND Ugly.

So What!You %#@ **^%&!

Sí, Amigo. N2 and O2.The Molecular Weight of N2 = 14 + 14 or 28.

The Molecular Weight of O2 = 16 + 16, or 32.

Which Is Heavier?

• Clearly, Our Hero, Hoppy, Has Established Mental Superiority and Taken the Upper Hand in This Debate.

Git to Your Point, Partner!

The MolecularWeight of H2O Is

1 + 1 + 16 or Only 18. Less Than That of

O2 or N2!

Which Is Heavier?

• Hoppy Takes On a Superior Air as He Finishes off His Opponent in the Coop d’Grass

Oh, I Knew That!

Accordingly, Dry Air Is Heavier

Because It Has A Smaller Fraction of H2O (Water Vapor)!

Pressure Gradients Drive Wind

Coriolis Effect Deflects Flow Direction

Upper Air Map - Altitude of 500 millibar “Surface”

LLLL HHHH

LL Units are meters X

10

Upper Air Flow

LLLL HHHH

LL

Jet Stream

LLLL HHHH

LL

Why Deserts?

• Rain Shadows• Global Circulation Patterns

Gas LawsGas Laws

PPV = V = nRnRTTP = PressureP = Pressure

T = Temperature T = Temperature P & T are on opposite sides of

equation, so they change in unison

Orographic Effects

Global CirculationGlobal Circulation

EquatorEquatorSun Hot Hot

ColdCold

HadleyHadley’’s Model s Model

EquatorEquatorSun

Hot Air Rises

Cold AirSinks

Simple Convection Simple Convection Cell in Each HemisphereCell in Each Hemisphere

Better Better Model Model

EquatorEquatorSun Hot, Wet Air

Cold, Dry Air

3 Convection Cells3 Convection Cellsin Each Hemispherein Each Hemisphere

2020--3030oo

5050--6060oo

Cool, Wet Air

Warm, Dry Air

Add CoriolisEffect…

to Produce

Prevailing Winds

Better Model Better Model

Wet HotWet HotSun

3 Convection Cells3 Convection Cellsin Each Hemispherein Each Hemisphere

Dry, HotDry, Hot

Wet, CoolWet, Cool

Dry, ColdDry, Cold

Dry, Hot Dry, Hot

Dry, Cold Dry, Cold

Wet, Cool Wet, Cool

Predict WorldPredict World’’s s DessertsDesserts

BAKLAVA,

DR. KITE’S 2ND

FAVORITE DESSERT

MIDDLE EASTERN DESSERT

Donkey (2001): You know what else everybody likes? Parfaits. Have you ever met a person, you say, "Let's get some parfait," they say, “* no, I don't like no parfait"? Parfaits are delicious.

"Now tell me, where are the others?!" (Lord Farquaad) "Eat me!" (Gingerbread man, spitting at him)

DESSERTS OF THE WORLD

Map Source: US CIA

Mmmm…Doughnuts

Images Sources for Desserts of the WorldParfait –

http://www.dcmarketingtools.com/gallery2/HW-catering.htmlBaklava –

http://www.cariskitchen.com/images/94HFBaklava.jpgApple Dumplin’s -

http://www.cariskitchen.com/images/94HF%20Apple%20Dumplings%20with%20Caramel%20Cinnamon%20Sauce.jpg

Black Forest Cake –http://www.cariskitchen.com/images/94PfaelzerBro%20Black%20Forest%20Cake.jpg

Moon Pie –http://www.moonpie.com/single/prod_level1.asp

Gingerbread Manhttp://coco.raceme.org/films/shrek/quotes/others.php

Donuts –http://witfits.blogspot.com/2005_03_01_witfits_archive.html

Summer Model

Thermal EquatorThermal Equator

SunEasterlies

Westerlies

Easterlies

““RealReal”” EquatorEquator

DESERTS OF THE WORLD

Antarctica = Desert

Why DidnWhy Didn’’t USA Wait IN t USA Wait IN 2003 to See if UN 2003 to See if UN Could DisarmCould DisarmIraq?Iraq?

EquatorEquatorSun

Climatic Considerations!Climatic Considerations!

Iraq Zagros Mts

P. Gulf

WinterModel

Sun

Easterlies

Westerlies

Easterlies

““RealReal”” EquatorEquator

Thermal EquatorThermal Equator

Sandstorm Iraq, Iran & Persian Gulf

visibleearth.nasa.gov/cgi-bin/

viewrecord?7746

Sandstorm Iraq, Iran & Persian Gulf

visibleearth.nasa.gov/cgi-bin/

viewrecord?7746

Dust StormIraq

March 2003

Dust in Deep-Sea Sediments

Aeolian Sediment Sources:Kite Stream, Antarctic Polar Desert

J.S. Kite Photo

Dry Bed of Kite Stream

J.S. Kite Photo

Wind-Blown Silt (Loess) Over Dry River Bed, New Zealand

Loess

Loess on Outwash Terrace, New Zealand

Mississippi River

System Loess

Last Ice Age~20,000 Years Old

Deflated Stream Bed

Desert Pavement

Wind Transportation of Sand

• Saltation

Antarctica: Ventifacts & Desert Pavement

Ventifact on Deflation Surface

Aeolian Sediments

DustDust

SandSand

Antarctica: Ventifact-Hoodoo

Coppice Dunes

Coppice Dunes, California

Deflation Surface

Kill Devil Hill, Kitty Hawk, NC

• Vegetated, Stable

J.S. Kite Photo

Jockeys Ridge, Kitty Hawk, NC

http://www.nature.nps.gov/nnl/Registry/USA_Map/States/NorthCarolina/NNL/NH/index.cfm

• Unvegetated, Unstable

NPS Photo

Dune Field, Victoria Valley, AntarcticaGlacier

Transverse Dunes

Dune in Later SlideJ.S. Kite Photo

Cross-Bedding in Dune

Wind Direction

Wind Direction

Sand Dune, Victoria Valley, Antarctica

J.S. Kite Photo

Lee Slip-Face of Dune, Victoria Valley

J.S. Kite Photo

Barchan Dune, Death Valley

Wind Direction

“Monster” Sand DuneVariable Wind Direction

Saudi Arabia