As the air warms, it begins to rise, creating a low pressure system. The higher it rises, the more the air cools. Water condenses as the air cools, creating clouds and rainfall. The air dries out as the rain falls. The result is warm, dry air, relatively high in our atmosphere.
Because of the lower air pressure, air rushes toward the equator from the north and south. As it warms, it rises, pushing the dry air away to the north and the south.
The dry air sinks as it cools, creating high-pressure areas and deserts to the north and south of the equator.
This is just one piece of how the Sun circulates air around the world--ocean currents, weather patterns and other factors also play a part. But in general, air moves from high-pressure to low-pressure areas, much the way that high-pressure air rushes from the mouth of an inflated balloon when you let go. Heat also generally moves from the warmer equator to the cooler poles.
Imagine a warm drink sitting on your desk--the air around the drink gets warmer as the drink gets colder. This happens on Earth on an enormous scale.
The Coriolis Effect, a product of the Earths rotation, affects this system as well. It causes large weather systems, like hurricanes, to rotate. It helps create westward-running trade winds near the equator and eastward-running jet streams in the northem and southem hemispheres. These wind patterns move moisture and air from one place to another, creating weather patterns.
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