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Climatology
Global Circulation Patterns Ch 4
30
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Undergraduate 4
03/16/2009

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Term
Where is the surplus energy from the Earth's surface radiated out of?
Definition
The poles
Term
What is the circulation of the atmosphere driven by?
Definition
Latitudinal temp. gradient. Oceans and atm combine to move excess heat poleward.
Term
What is the pressure gradient force?
Definition
push as the air moves from high pressure to low pressure.
Term
What 3 factors control winds?
Definition
The PGF, Coriolis Effect/Acceleration, friction
Term
Why do the upper westerlies exist?
Definition
unequal heating of the earth causes a latitudinal temp. gradient, causes pressure surfaces to slope poleward.
Term
What is the circumpolar vortex?
Definition
upper level flow is geostrophic (westerly), meanders in Rosby Waves, can be zonal/azonal, with ridges and troughs
Term
What does Azonal refer to?
Definition
meridional flow, N-S, meanders
Term
What does Zonal refer to?
Definition
straight W-E winds
Term
The upper air pattern most conductive to cyclone development is ______ because this pattern creates large variations in absolute vorticity.
Definition
Azonal
Term
What are Rosby Waves?
Definition
Horizonal Meanders
Term
What are some characteristics of the Polar Front Jet Stream/Upper Level Westerly?
Definition
surface goes from warm to cold quickly. slope drops quickly, fast geostrophic winds.
Term
What is Vorticity?
Definition
Spin or rotation of air parcel around local vertical
Term
What is relative vorticity and what is it determined by?
Definition
local rotation that can be + or -. curvature or shear.
Term
Where is relative vorticity + and -
Definition
+ in troughs, - in ridges.
Term
How is area affected by vorticity increasing and decreasing?
Definition
as vorticity increases, area decreases.
vorticity decreases, area increases
Term
What is divergence of air masses?
Definition
air moving out of a slow area into a fast one.
Term
what are the characteristics of a high pressure anticyclone?
Definition
warming air, no clouds, mid-level inversion, warm clear weather.
Term
what are the characteristics of a cyclone?
Definition
low pressure, adiabatic cooling, storms, clouds
Term
what does upper level divergence create?
Definition
air pushed downwards, surface divergence, anticyclone
Term
what does upper level divergence create?
Definition
decreasing area vorticity, upper level divergence pulls air up.
Term
Where does absolute vorticity tend to be conserved?
Definition
in the air parcel, short time scales,
Term
Where do both earth and absolute vorticity increase in the rosby waves?
Definition
poleward. There is a decrease in relative vorticity in order for the waves to remain constant
Term
How does a mountain range impact air masses?
Definition
-air mass forced up, squeezed into smaller depth column. relative vorticity decreases, must curve to the clockwise direction. Once it moves over the mountain, air mass spreads out, depth increases, RV must increase. curve straightens, heads up to high lat to conserve RV, trough forms downwind of mtn range
Term
what is an air mass?
Definition
a large homogenous segment of the atm, that is near uniform in terms of stability, temp and humidity
Term
What is a source region?
Definition
an area that gives its characteristics to the air mass. Flat, uniform region. Anticyclonic conditions predominate. (descending divergent air, promotes contact with the surface. low winds.)
Term
an air mass moving over a warm area becomes ____ while an air mass moving over a cool area becomes _____
Definition
destabilized, stabilized
Term
What air mass characteristics get modified by the land surface below as the air mass moves over it?
Definition
temp, moisture, stability.
Term
Define a front?
Definition
boundary zone between air masses. named by which is pushing the other out of the way. less dense air mass is shoveled up and lifted. weather produced.
Term
What are 4 things a front can produce?
Definition
convection, temperature/humidity changes and wind shifts
Term
What causes an onshore flow in coastal areas?
Definition
warming of the land during the day produces thermal L over the land. cooler marine air is at H pressure. air flow from H to L pressure starts
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