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Thinking about the Wind
WindWind is the horizontal movement of air from an area of high pressure to an area of low pressure.
All winds are causes by differences in air pressure.
Wind SpeedWinds are described by their direction and speed. The name of a wind tells you where the wind is coming FROM. For example, a south wind blows from the south to the north.
Wind speed is measure by an anemometer.
Wind ChillYou have all heard weather reports that talk about wind chill.
A wind-chill factor is the increased cooling that a wind can cause. The weather report might say, "the temperature is 20 degrees Farenheit wilth a wind-chill makes it feel like 18 degrees below zero.
LOCAL AND GLOBAL WINDSThe two types of winds are:
LOCAL AND GLOBAL
A local wind is a wind that blows over a short distance. Local winds are caused by unequal heating of Earth's surface within a SMALL area.
A wind that blows FROM an ocean or lake is called a sea or lake breeze.
The flow of air FROM land to water is called a land breeze.
GLOBAL WINDSWinds that blow steadily from specific directions over long distances are called GLOBAL WINDS. Global winds are created by unequal heating of Earth's surface.
GLOBAL WIND BELTSThere are four major wind belts.
DOLDRUMS - Near the equator the sun heats the surface strongly. Warm air rises creating an area of low pressure. There is very little horizontal motion, so the winds near the equator are very weak.
HORSE LATITUDESWarm air that rises at the equator divides and flows both north and south. At about 30 degrees north and south the air stops moving toward the poles and sinks. In each of these regions another belt of calm air forms. It is said that because of the calm air, sailors hundreds of years ago had to throw horses overboard because they ran out of food and water....that is where the name comes from.
Thinking about the Horse Latitudes
Trade Winds and Prevailing WesterliesSteady easterly winds are called Trade Winds These winds blow from the horse latitudes toward the equator.
In the Northern Hemisphere, these winds blow from the northeast.
In the Southern Hemisphere, these winds blow from the southeast.
In the mid-latitudes, winds that blow toward the poles are turned toward the east because of something called the Coriolis Effect. These are the prevailing westerlies because they blow from west to east
Coriolis EffectThe way Earth's rotation makes winds curve is called the Coriolis Effect.
JET STREAMSAbout 10 km above Earth's surface are bands of high speed winds called jet streams.
When airplanes are traveling east they are aided by the jet stream. Pilots can save fuel and time by traveling east in a jet stream.
Wind can be used to turn a turbine and create electricity.
Wind power plants are called "wind farms."
Wind energy is free and does not cause pollution.
Wind energy is not ideal for all locations. Winds have to blow steadily enough to be a worthwhile energy source.