Transcript Wind Patterns

Wind Patterns
Wind Patterns on a Spherical Earth
The spherical shape of the
Earth causes Earth’s
uneven heating.
 The Earth is heated more
around the equator and
cooler around the poles.
 These conditions initiate
the worldwide movements
of air.

Wind Patterns on a Spherical Earth
 We
know that warm air is lighter and less dense,
therefore it rises.
 We
know that cool air is heavier and drops,
therefore it flows under the warmer air.
Wind Patterns on a Spherical Earth
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By the time the air reaches
north or south latitudes of
about 30º, the air has cooled
enough that it begins to drop
back to the earth’s surface.
When the air reaches the Earth,
some moves up toward the
pole, some move back towards
the equator.
Wind Patterns on a Spherical Earth
At the same time, cold air
is flowing from the poles
to the equator.
 By the time the air reaches
60º, it has warmed enough
to begin to rise again.
 The result, three distinct
closed patterns of air
movement.

Wind Patterns on a Rotating Earth
If the Earth did not rotate,
the prevailing wind
patterns would be to the
north or south.
Wind Patterns on a Rotating Earth
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If the atmosphere stood still
while we rotated underneath it,
we would feel a strong wind
(~300m/s).
We don’t feel this, therefore,
the atmosphere must move
with the Earth.
Different parts of the earth
travel at different speeds
(because it is a sphere).
Wind Patterns on a Rotating Earth
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As a result, when air begins to
move north and south due to
convection it also moves east.
Two points on the same
longitude but different latitudes
move at different speeds
causing a curve in the winds.
The influence of the Earth’s
rotation on air is called the
Coriolis Effect.
Wind Patterns on a Rotating Earth
In the central part of the Northern Hemisphere, the
Coriolis effect causes winds to blow West to East
(Prevailing Westerlies).
http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/fw/crls.rxml
http://www.classzone.com/books/earth_science/terc/content/
visualizations/es1904/es1904page01.cfm?chapter_no=visu
alization
http://www.eoascientific.com/campus/earth/multimedia/corio
lis/view_interactive
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