In Deserts, Forests and Grasslands you learned that a desert is a very dry place. Deserts cover about a third of Earth's land, and they are not all hot.
Key idea
A desert is a place that gets very little precipitation, usually less than 250 mm (10 inches) a year. The Sahara is the largest hot desert. The Atacama is the driest place outside the poles. Antarctica is the largest desert of all.
| Desert | Where | Kind |
|---|---|---|
| Sahara | North Africa | Hot; about 9.2 million km² |
| Arabian (Rub' al Khali) | Arabian Peninsula | Hot |
| Kalahari and Namib | Southern Africa | Hot; the Namib is on the coast |
| Atacama | Chile and Peru, South America | Cool coastal desert; the driest outside the poles |
| Gobi | Mongolia and China | Cold: freezing winters |
| Great Victoria and others | Australia | Hot |
| Antarctica | The South Pole | Cold; about 14 million km² |
Why it works
Most hot deserts sit near 20° to 30° north and south of the equator. Air that rises over the equator drops its rain there, then sinks again near those latitudes as dry air, so clouds rarely form. Other deserts form in the rain shadow of mountains (the Atacama is shielded by the Andes) or deep inside continents, far from the ocean (the Gobi). Antarctica counts because almost no new snow falls there each year.
Worked example: Hot or cold?
The Gobi is in Mongolia, far from any ocean. It is very dry. Is it a hot desert?
- It is far north (about 40° to 45° N) and far inland.
- Its winters are long and freezing.
Answer: No. The Gobi is a cold desert.
Common mistake
Thinking a desert must be hot and sandy. A desert is defined by dryness, not heat. Antarctica and the Gobi are cold deserts, and most deserts are rock and gravel, not sand dunes.