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When the Sun beats down on the equator war, moist air begins to rise.  As it rises, the air cools and loses its moisture as rain that sustains rainforests near the equator.  Convection currents carry the now dry air farther north and south.  Some of this dry air descends as the tropics, where it creates a zone of deserts.

Rain Forest:  The rain forest zone forms a belt that encircles the globe on either side of the equator.  The photograph below shows a rain forest near the Congo River in central Africa.

Desert:  Like many of the great desert regions of the world, the Sahara, in northern Africa, is largely a result of atmospheric convection currents.  Here, a group of nomads gather near a dried-up river in Mali.

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Surprising Thermal Energy

Did you know…

... The average amount of solar energy that reaches the United States each year is about 600 times greater than the nation’s annual energy demands.

...When a space shuttle reenters Earth's atmosphere at more than 28,000 km/h, its outer surface is heated by friction to nearly 1,650 degrees celsius.  This temperature is high enough to melt steel.

...A lightning bolt heats the air in its path to temperatures of about 25,000 degrees celsius.  That’s about 4 times hotter than the average temperature on the surface of the Sun.