Deserts cover about one-fifth of the world ("Desert") and are usually located between 15 and 30 degrees north and south of the equator ("The Desert Environment"), or another way of saying it, the land between the Tropic of Cancer, and the Tropic of Capricorn (Baker p6). A lot of deserts are right next to the mountains because as the warm moist air cools down on the mountaintops, precipitation occurs. When the air reaches the other side of the mountain, there is few or no moisture left in the water vapor, and there will be an insufficient amount of rain. Thus, deserts are formed ("The Desert Biome"). The winds that blow to the desert areas are also dry, since its origin is far away, and most of its moisture has been given off along the way (Baker p7). Numerous deserts are also near coastal areas. The cold ocean currents move toward...