World Geography Principal Deserts of the World Deserts are arid regions, generally receiving less than ten inches of precipitation a year, or regions where the potential evaporation rate is twice as great as the precipitation. The world's deserts are divided into four categories.
Subtropical deserts are the hottest, with parched terrain and rapid evaporation.
Although cool coastal deserts are located within the same latitudes as subtropical deserts, the average temperature is much cooler because of frigid offshore ocean currents. Polar regions are also considered to be deserts because nearly all moisture in these areas is locked up in the form of ice. The world's largest nonpolar desert gets its name from the Arabic word Sahra' , meaning desert Arabian Saudi Arabia, Kuwait, Qatar, United Arab Emirates, Oman, Yemen 1 million sq. Sandhills, gravel, grass. Gravel plains Atacama Chile 54,000 sq.