... slopes of the mountains— Figure Rain-shadow deserts such as the Mojave and Great Basin deserts of the American Southwest form on the leeward side of mountains Atlas of the world's deserts 18 The. .. caused by the way in which the sun’s rays warm the earth The part of the earth that receives most of the sun’s heat is the tropics the region about the equator that lies between the tropics of Cancer... of the world the desert is not a remote fantasy but a reality that impinges on their everyday lives Atlas of the world's deserts Defining the desert Definitions of the term “desert” are neither