ABSTRACT
Deserts occur on a consistent basis north and south of the equator loosely aligning themselves with the Tropic of Cancer and the 30°N parallel and the Tropic of Capricorn and the 30°S parallel. All or parts of the five main North American deserts occur within the territorial boundaries of the US The five American deserts are located predominately between two major mountain ranges. The Colorado Desert was so named by early Spanish explorers, because the Colorado River serves as its eastern boundary. The Sonoran is the most variable of North American deserts, being either extremely lush, as deserts go or extremely hot or dry. The desert environment is marked by extremes: hot and cold; day and night; summer and winter; wet and dry. The availability of water, as it pertains to desert environments, is not always just a measurement of mean annual precipitation, but also is a function of the rate of evaporation.
