Transcript 18CirculationT6 - Arizona State University

Earth’s Circulation
Atmospheric Circulation
Ocean 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 Winds
Flow to
the Intertropical
Convergence
Zone
Hadley Cells
• Touch at ITCZ
• Rising air over Doldrums
• Fed by Easterly Trade Winds
Trade Winds Carry Dust
Dust Plume blowing
from the east
Mali
Classroom Resource
Watch 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 Resources
Watch 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 Resource
Watch 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
currents
transport
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 days
Classroom Resource
Cold Currents: Upwelling & Rich
Nutrients result in Marine Resources
Classroom Resources
Movie with labels
Focus on Peru to
introduce El Nino
Classroom Resources
ENSO: El Nino Southern Oscillation
“Normal” or more typical (La Nina is the
more normal state)
Trade winds push
warm water &
storms to
East Pacific
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
• Trade winds
decrease
• warmth & storms
move eastward
against South
America
• Upwelling
ceases
• Marine food
chain collapse
A Flip-flop
across the
South
Pacific
(pressures
oscillate)
ENSOred
On
Average
7 yrs apart
In review:
In review:
Online Resources
El Nino/La Nina Visualizations
http://serc.carleton.edu/NAGTWorkshops/visualization/collections/elnin
o_lanina.html
Oceanography Animations
http://serc.carleton.edu/NAGTWorkshops/visualization/collections/ocea
nography.html
Ocean Upwelling and Circulation
http://serc.carleton.edu/NAGTWorkshops/visualization/collections/circul
ation_upwellings.html
Ocean Surface Currents
http://serc.carleton.edu/NAGTWorkshops/visualization/collections/surfa
cecurrents.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.