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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.