Global Atmospheric Circulation Flashcards

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1
Q

What is global circulation?

A

In 1735 George Hadley declared that temperature contrasts between Poles and Equator drives global circulation.

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2
Q

The one-cell model for global circulation would work great except….

A

Works great for a non-rotating earth!

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3
Q

What does the rotation of the earth do to winds?

A

Rotation causes winds to be deflected

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4
Q

What do one cell and 3 cell models look like?

A

Look at power point on page 4. Make sure you know 3 cell model VERY well

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5
Q

What does a 3 cell model work best for?

A

A rotating, all water earth

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6
Q

What are the two general rules on pressure/weather relationship?

A
  • areas of L have clouds and rain

* areas of H have fair weather High and Dry!

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7
Q

What is the equatorial low also called?

A

ITCZ (Inter Tropical Convergence Zone)

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8
Q

In the Inter Tropical Convergence Zone, why does air rise in the troposphere?

A

Air rises to tropopause due to intense heating (THERMAL LOW Pressure) diverges aloft and moves toward poles

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9
Q

What are light winds called in the Inter Tropical Convergence Zone?

A

Doldrums

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10
Q

What is the weather like in the Inter Tropical Convergence Zone?

A

Constant clouds and rain

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11
Q

What is found at (20º-35º) each hemisphere?

A

Subtropical High pressure (STH)

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12
Q

What happens to the air in the Subtropical High Pressure zone?

A

air aloft cools and sinks

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13
Q

Why does air cool in the Subtropical High Pressure zone? Why does it sink?

A

Air Cools due to radiative heat loss into space. Heavier cool air piles up aloft and sinks

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14
Q

What does cooling and sinking air create in Subtropical High Pressure zones?

A

Creates DYNAMIC High Pressure zone. Sinking air is warming = DESERTS!!!

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15
Q

What are trade winds?

A

Surface air flows from STH to ITCZ, deflected to right, produces steady easterly winds, 11-13 mph

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16
Q

What are prevailing westerlies? What happens to them?

A

Sinking air from STH diverges at surface and flows toward subpolar low between about 30º to 60º N & S, deflected by coriolis

17
Q

What do the westerlies produce?

A

Stormy weather

18
Q

Where are westerlie winds especially strong?

A

Winds are especially strong between 40-50° the Roaring 40s and in southern hemisphere

19
Q

What is a subpolar low also known as?

A

Also called Polar Front (“front” = where 2 air masses meet)

20
Q

What is a subpolar low (polar front)

A

Warm air (subtropics) vs. cold air (polar) around 60º…warm is forced up over cold, creating DYNAMIC LOW pressure at surface (NOT from thermal heating)

21
Q

What is a polar high?

A

It is when air loses heat to space, and is chilled as it flows over snow/ice. It then sinks around poles forming Thermal High

22
Q

What are polar easterlies?

A

Air flows from Polar H to Polar Front (L).

23
Q

What happens to air in polar easterlies? What is it deflected by?

A

Air subsides at poles (H) and flows toward polar front (L), deflected by coriolis effect to easterly wind

24
Q

The 3-Cell is an “all water world” MODEL. Real circulation pattern is much more complicated. Why?

A

Continents (landmasses) disrupt the ideal pattern of thermal pressure land heats and cools faster than water. This means there is uneven Heating of Land and Water

25
Q

What are idealized winds?

A

Idealized winds generated by pressure gradient and Coriolis Force.

26
Q

What are actual winds?

A

Actual wind patterns owing to land mass distribution.

27
Q

What are the observed patterns of pressure cells?

A

LARGE Pressure Cells

28
Q

What do continents disrupt?

A

Continents disrupt zonal (latitudinal) flow

29
Q

Why do High and Low pressure cells form?

A

H and L Pressure cells form due to land/water contrasts and surface friction

30
Q

What happens in the Southern Hemisphere?

A

In the S. Hemisphere, at mid and high lats (45º & 65ºS), a more zonal (latitudinal) pattern exists (like all water world). This is because there are Few and Smaller LAND SURFACES

31
Q

What is important to know about pressure and wind belts?

A

Pressure & wind belts are NOT fixed they migrate N and S as sun’s direct rays move North and South

32
Q

How many major high pressure cells are there?

A

5

33
Q

What are winds named after?

A

Winds are named from where they come!!

34
Q

What is a monsoon?

A

Seasonal Wind REVERSAL (caused by pressure reversal). Like a land/sea breeze but Operates on seasonal NOT daily schedule. (Major seasonal change in pressure, wind direction, and rainfall occurs)

35
Q

Where do we find monsoonal climates?

A

India and South East Asia. There is also a North American Monsoon that is in SW US and N Mexico.