Earth’s Circulation

Atmospheric CirculationOcean Circulation

Circulation is the way Earth moves ocean water and atmosphere

General Circulation of the Atmosphere: start with surface winds

Surface Winds: Follow Pressures

• Flow high to low

• Coriolis

• Friction

First step – naming winds

Trade WindsFlow to

the Intertropical Convergence

Zone

Hadley Cells• Touch at ITCZ• Rising air over Doldrums• Fed by Easterly Trade Winds

Trade Winds Carry Dust

MaliDust Plume blowing

from the east

Classroom ResourceWatch trade winds flow from east to west,

Different visuals of flow of moisture

Your tropical vacation and

the trade winds

ITCZ: Rain Maker

Lion King: Rain Came from ITCZ

movement, following the sun

Classroom ResourcesWatch ITCZ move north and south

Sahel: at the margin of the ITCZ, so some years lots some little

Descending air

A big cause of deserts is descending air, right under subtropical high

Subtropical High Pressures are “centered” in oceans

Classroom ResourceWatch westerly winds flow from west to east

Different visuals of flow of moisture

Polar Front: zone of storms from convergence of westerly winds and

polar easterly winds

Polar Easterlies

-Flowing from Polar High to Polar Front (low)

Air descends

Prof. Cerveny’s Study Guide

Now – add the vertical in 3D

Continents break up the high pressures and make reality look

more like circulation cells

3D cross section tells the story:rain – rising air

dry – descending air

“center” of the precipitation peaks are the belts of low pressure: ITCZ and the 2 polar fronts

Jet Streams direct our storms

Different Patterns

For Arizona to get winter rains, needs:• Winter time for jet stream to shift south

For Arizona to get winter rains, needs:• Meriodional pattern

• The “trough” to be over Az

Polar Jet separates cold/warm

Cold outbreaks in East when jet moves in cold air

Ocean Circulation around Gyres

warm currentstransport energy

Surplus in Tropics moved to higher latitudes by warm currents

Larger Picture

Classroom Resources

Gulf Stream 3D perspective

What would happen if Gulf Stream slowed or didn’t go far enough?

Gulf stream &

North Atlantic Drift

Classroom Resource

It happened in Younger Dryas

“The Day After”: decades not daysClassroom Resource

Cold Currents: Upwelling & Rich Nutrients result in Marine Resources

Classroom Resources

Movie with labels

Focus on Peru to introduce El Nino

Classroom Resources

“Normal” or more typical (La Nina is the more normal state)

Trade winds push

warm water &

storms to

East Pacific

ENSO: El Nino Southern Oscillation

Part of the “Walker Cell”

Trade winds and warm water supplies energy (storms) to Northern Australia and Indonesia, while Peru is dry from descending air

ENSO: El Nino Southern Oscillation

• Upwelling ceases• Marine food chain

collapse

• Trade winds decrease

• warmth & storms move eastward against South America

A Flip-flopacross the

SouthPacific

(pressures oscillate)

On

Average

7 yrs apart

ENSO-

red

In review:

In review:

Online Resources

El Nino/La Nina Visualizations

http://serc.carleton.edu/NAGTWorkshops/visualization/collections/elnino_lanina.html

Oceanography Animations

http://serc.carleton.edu/NAGTWorkshops/visualization/collections/oceanography.html

Ocean Upwelling and Circulation

http://serc.carleton.edu/NAGTWorkshops/visualization/collections/circulation_upwellings.html

Ocean Surface Currents

http://serc.carleton.edu/NAGTWorkshops/visualization/collections/surfacecurrents.html

Circulation is the way Earth moves ocean water and atmosphere

Imagery seen in this presentation is courtesy of Ron Dorn and other ASU colleagues, students and colleagues in other academic departments, individual illustrations in scholarly journals such as Science and Nature, scholarly societies such as the Association of American Geographers, city,state governments, other countries government websites and U.S. government agencies such as NASA, USGS, NRCS, Library of Congress, U.S. Fish and Wildlife Service USAID and NOAA.