Deserts cover approximately one fifth of the world’s surface and fall in roughly the same latitudes all around the globe: between 15 and 35 degrees. In the Southern Hemisphere, this area falls roughly over the Tropic of Capricorn, while in the Northern Hemisphere it is closer to the Tropic of Cancer. There are three general varieties: the rain shadow desert, the coastal desert, and the remote interior basin desert.
The climate in desert ecosystems is highly varied, but a few common characteristics do emerge when defining a desert. These characteristics are: