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General Wind Formation Steps:
1. The sun’s rays warm the earth.
2. Earth radiates heat and warms the surrounding air.
3. Cold air is warmed and becomes less dense.
4. Less dense air will rise.
5. As air rises it expands and cools.
6. Cool air which is denser sinks and causes an increase in air pressure.
7. Wind is formed.
--------------------------------------------------------Global Wind Patterns
The region of Earth receiving the Sun's direct rays is the equator. Here, air is heated and rises,
leaving low pressure areas behind. Moving to about thirty degrees north and south of the equator,
the warm air from the equator begins to cool and sink. Between thirty degrees latitude and the
equator, most of the cooling sinking air moves back to the equator. The rest of the air flows toward
the poles. The air movements toward the equator are called trade winds- warm, steady breezes that
blow almost continuously. The Coriolis Effect makes the trade winds appear to be curving to the
west, whether they are traveling to the equator from the south or north.
The trade winds coming from the south and the north meet near the equator. These converging
trade winds produce general upward winds as they are heated, so there are no steady surface winds.
This area of calm is called the doldrums.
Between thirty and sixty degrees latitude, the winds that move toward the poles appear to curve to
the east. Because winds are named from the direction in which they originate, these winds are
calledprevailing westerlies. Prevailing westerlies in the Northern Hemisphere are responsible for
many of the weather movements across the United States and Canada.
At about sixty degrees latitude in both hemispheres, the prevailing westerlies join with polar
easterlies to reduce upward motion. The polar easterlies form when the atmosphere over the poles
cools. This cool air then sinks and spreads over the surface. As the air flows away from the poles, it
is turned to the west by the Coriolis effect. Again, because these winds begin in the east, they are
called easterlies.
Resource: http://kids.earth.nasa.gov/archive/nino/global.html
Resource: http://www.docstoc.com/docs/78527976/Global-Wind-Patterns
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Local Winds
Land & Sea Breezes differ according to heating and cooling during the Night & Day.
Resources:
https://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&docid=bUMv1QOt6Y6ptM&tbnid=6VFI2SJJR
RrH2M:&ved=0CAQQjB0&url=http%3A%2F%2Fgpsscience8.wikispaces.com%2Flocal%2Bwinds&ei=2KH7UumHJfHG0AGf3YBo&bvm=bv.61190604,d.eW0&psig=AFQjCNFgyRh7wXE
-dqmCH3gjBncmfKAxdA&ust=1392308906235465
http://www.eduplace.com/science/hmxs/es/pdf/5rs_3_9-3.pdf
Local Winds
Small-scale convection currents arise from uneven heating on a
smaller scale. This kind of heating occurs along a coast and in
the mountains. Small-scale convection currents cause local winds.
Local winds blow over a much smaller area and change direction
and speed over a shorter period of time than global winds.
Sea Breeze
On a hot summer day at the beach,
the land heats up faster than the
water. The warmer air over land rises,
while the cooler air over the ocean
rushes in to take its place. This wind
is called a sea, or onshore, breeze.
Land Breeze
After sunset, the land cools down
faster than the water. The warmer
air over the ocean rises, while the
cooler air over land rushes in to take
its place. This wind is called a land,
or offshore, breeze.