What is a desert?
First, let's start with defining a desert. Areas receiving less than 10 inches of rain a year used to be considered deserts, but that included areas that didn't look like deserts. So now, to be considered a desert, the area receives less than 10 inches of rain and evaporates more than 10 inches of rain per year. There are four deserts in North America: The Great Basin, Mojave, Chihuahuan, and Sonoran.
Where is it?
The Sonoran Desert occurs primarily in Mexico. More than two-thirds of its total area is in Baja California and the state of Sonora. In the United States, most of the Sonoran Desert can be found in the southern third of Arizona, with small areas in southeastern California. It is a subtropical desert and the most complex desert in North America. It has great diversity in geological structures as well as the number and variety of plants and animals.
One reason for the many plants and animals in the Sonoran Desert is that it receives rainfall bi-seasonally. Rain falls in this desert during the winter months and also in July and August. Because the rain occurs twice a year, the plants don't have to wait so long between drinks.
Last updated: February 24, 2015