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. Cold winter deserts are marked by stark temperature differences from season to season, ranging from 100° F (38° C) in the summer to 10° F (–12° C) in the winter. Polar regions are also considered to be deserts because nearly all moisture in these areas is locked up in the form of ice.
| Desert | Location | Size | Topography |
| SUBTROPICAL DESERTS | |||
| Sahara | Morocco, Western Sahara, Algeria, Tunisia, Libya, Egypt, Mauritania, Mali, Niger, Chad, Ethiopia, Eritrea, Somalia | 3.5 million sq. mi. | 70% gravel plains, sand, and dunes. Contrary to popular belief, the desert is only 30% sand. 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. mi. | Gravel plains, rocky highlands; one-fourth is the Rub al-Khali (“Empty Quarter”), the world's largest expanse of unbroken sand |
| Kalahari | Botswana, South Africa, Namibia | 220,000 sq. mi. | Sand sheets, longitudinal dunes |
| Australian Desert | | | |
| Gibson | Australia (southern portion of the Western Desert) | 120,000 sq. mi. | Sandhills, gravel, grass. These three regions of desert are collectively referred to as the Great Western Desert—otherwise known as “the Outback.” Contains Ayers Rock, or Uluru, one of the world's largest monoliths |
| Great Sandy | Australia (northern portion of the Western Desert) | 150,000 sq. mi. | |
| Great Victoria | Australia (southernmost portion of the Western Desert) | 250,000 sq. mi. | |
| Simpson and Sturt Stony | Australia (eastern half of the continent) | 56,000 sq. mi. | Simpson's straight, parallel sand dunes are the longest in the world—up to 125 mi. Encompasses the Stewart Stony Desert, named for the Australian explorer |
| Mojave | U.S.: Arizona, Colorado, Nevada, Utah, California | 54,000 sq. mi. | Mountain chains, dry alkaline lake beds, calcium carbonate dunes |
| Sonoran | U.S.: Arizona, California; Mexico | 120,000 sq. mi. | Basins and plains bordered by mountain ridges; home to the Saguaro cactus |
| Chihuahuan | Mexico; southwestern U.S. | 175,000 sq. mi. | Shrub desert; largest in North America |
| Thar | India, Pakistan | 175,000 sq. mi. | Rocky sand and sand dunes |
| COOL COASTAL DESERTS | |||
| Namib | Angola, Namibia, South Africa | 13,000 sq. mi. | Gravel plains |
| Atacama | Chile | 54,000 sq. mi. | Salt basins, sand, lava; world's driest desert |
| COLD WINTER DESERTS | |||
| Great Basin | U.S.: Nevada, Oregon, Utah | 190,000 sq. mi. | Mountain ridges, valleys, 1% sand dunes |
| Colorado Plateau | U.S.: Arizona, Colorado, New Mexico, Utah, Wyoming | 130,000 sq. mi. | Sedimentary rock, mesas, and plateaus—includes the Grand Canyon and is also called the “Painted Desert” because of the spectacular colors in its rocks and canyons |
| Patagonian | Argentina | 260,000 sq. mi. | Gravel plains, plateaus, basalt sheets |
| Kara-Kum | Uzbekistan, Turkmenistan | 135,000 sq. mi. | 90% gray layered sand—name means “black sand” |
| Kyzyl-Kum | Uzbekistan, Turkmenistan, Kazakhstan | 115,000 sq. mi. | Sands, rock—name means “red sand” |
| Iranian | Iran | 100,000 sq. mi. | Salt, gravel, rock |
| Taklamakan | China | 105,000 sq. mi. | Sand, dunes, gravel |
| Gobi | China, Mongolia | 500,000 sq. mi. | Stony, sandy soil, steppes (dry grasslands) |
| POLAR | |||
| Arctic | U.S., Canada, Greenland, Iceland, Norway, Sweden, Finland, Russia | 5.4 million sq. mi. | Snow, glaciers, tundra |
| Antarctic | Antarctica | 5.5 million sq. mi. | Ice, snow, bedrock |
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