Ch. 23.3 Winds

1
Ch. 23.3 Winds
2

• Low air pressure at the equator, due to the
  constant rising of heated air.
• Cold heavy air at the poles sinks, causing high
  pressure regions.
• Pressure differences create worldwide air
  movement (winds)air moves from high pressure to
  low pressure.

3
Global Winds

• The Coriolis force causes winds to be deflected
  to the right in the N. Hemisphere, and
  to the left in the S. Hemisphere. Greatest
  effect at the poles.
• Warm air rising at the equator spreads poleward
  in both directions.
• Some sinks at 30 degrees latitude, forming high
  pressure zones with air flowing away both north
  and south.

4

• At 60 degrees latitude, surface air from the
  polar highs meets the air flowing from the 30
  degree highs.
• Converging air rises, forming low pressure areas
  at 60 degrees latitude.
• The three looping patterns of flow in each
  hemisphere are called convection cells.

5
(No Transcript)
6

• Look up and define trade winds, doldrums, horse
  latitudes, westerlies, polar easterlies

7
Wind and Pressure Shifts

• Yearly seasonal cycles mean that the global wind
  belts shift about 10 degrees of latitude during
  the course of a year.

8
Local Winds

• Breezesgentle winds that extend less than 100
  km.
• Often caused by local conditions that produce
  temperature differences.

9
Land and Sea Breezes

• Land heats up faster than water when both receive
  equal sunlight.
• During daylight, warmed air above land rises,
  creating low pressure.
• Cooler air from over the water moves in to
  replace ita sea breeze.
• At night, the reverse occurs, the land cools
  faster, and a land breeze develops.

10
(No Transcript)
11
(No Transcript)
12
Mountain and Valley Breezes

• During daytime, warmed air in valleys moves up
  mountain slopesa valley breeze.
• At night, in the quickly cooling mountains, cold
  mountain air flows downhill into the valleys, a
  mountain breeze.