Transcript Chapter 23.3

Ch. 23.3 Winds



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.
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.



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.

Look up and define: trade winds,
doldrums, horse latitudes, westerlies,
polar easterlies
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.
Local Winds


Breezes—gentle winds that extend
less than 100 km.
Often caused by local conditions that
produce temperature differences.
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 it…a sea breeze.
At night, the reverse occurs, the land
cools faster, and a land breeze
develops.
Mountain and Valley Breezes


During daytime, warmed air in
valleys moves up mountain slopes…a
valley breeze.
At night, in the quickly cooling
mountains, cold mountain air flows
downhill into the valleys, a mountain
breeze.