Why Are Deserts Hot?
Not all deserts are hot!
Because the definition of a desert is that it lacks moisture, a desert is not defined as being hot. For example, the Atacama Desert in Chile is considered the driest place on earth and it is rather cold for a desert, with daily temps from 32°F to 77°F (1). Some deserts are cold because of their altitude, some are cold because they are so far from the equator (polar deserts) and others are cold because of a dominant cold wind flow.
Here's a couple reasons why some deserts are hot:
1) Many deserts are largely influenced by something called a subtropical high pressure (described in How do deserts form?). Subtropical refers to it's location, out of the tropics. High pressure is an area of sinking air. As air sinks, it heats up. Not only that, but the warmer air will aid in evaporating water. So, Under a large area of high pressure that rarely moves, there is sinking air which warms the earth and evaporates water from the soil...perfect for a hot desert!
2) Sunlight energy can be used to evaporate water. If there is little to no water to evaporate, then all of that sunlight energy is absorbed by the earth. Then the earth emits more energy into the air thus heating the air even more.
3) The closer a desert is to the equator, the closer it is to the most intense sunshine all year long. The more intense the sunshine, the hotter the land and air will get.
Some Examples of Hot and Cold Deserts :
Hot Deserts- Australian
- Arabian, Arabian Peninsula
- Mojave, US (Arizona, California, Nevada)
- Sahara, Northern Africa
- Sonoran, US (Arizona, California) & Mexico
Cold Deserts
- Atacama, Chile/Peru
- Gobi, Northern China/Southern Mongolia
- Great Basin, US (Idaho, Nevada, Oregon & Utah)
- Namib, Coasts of Southwestern Africa
- Turkestan, Parts of Middle East & Russia