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Radiant energy from the Sun helps to heat the earth. Because the earth is curved, The equator receives more direct sunlight. This causes air at the equator to have more energy. More energy means more particles collide. The particles move away from each other to create a situation where warm air has less particles per unit volume than cool air does.  Warm air therefore is less compacted and less Dense than cool air. Warm air will rise upward while cooler more dense air will sink under it. This movement of air is Wind.  Warm air rising at the Equator being replaced by cooler air sinking at the North and South Pole. 

Surface Winds called trade winds and prevailing westerlies move in opposite directions. These winds move vast amounts of air around. Near the upper Troposphere, narrow belts of strong moving wind, called jet streams, move storms across our country. Jet streams can push a plane, so pilots take advantage of this moving air.

Near the equator, there is very little wind. This area is called the doldrums.

Moving air seems to curve as it moves across the earth. This is because the earth rotates. Imagine standing on a Merry Go Round and throwing a ball to your friend ion the other side. Your friend would move as the ride turned and would miss the ball. The ball would appear to curve as does the wind on the spinning earth.

In this Investigation...

Students will build a barometer and find out how air pressure and convection currents cause wind.

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