Why is the desert hot by day and cold at night?
Because desert air is dry and the sky is clear. With almost no water vapor or clouds, sunlight hits the ground at full strength by day, and at night the heat escapes straight to space. Daily swings of 30 to 40°F are common.
Show me why1 min
No blanket
Water vapor is the atmosphere's main heat-trapping gas. Humid places stay warm at night because vapor and clouds absorb the heat the ground gives off and send some back. Desert air has so little water that the heat sails through it, so the ground and the air above it cool fast after sunset.
Go deeper2 more
Sand and rock heat fast
Dry sand and rock warm quickly because there's no moisture to evaporate and no plants to shade them. Desert ground can get far hotter than the air: well over 150°F at the surface on a summer afternoon, hot enough to burn bare feet.
Why deserts form
Most big deserts sit where air sinks (around 30° north and south of the equator, under permanent high pressure), in the rain shadow of mountains, or far inland from any ocean. Cold ocean currents dry out coastal deserts like the Atacama and Namib.
Questions people ask
- Do deserts get cold in winter?
- Yes. Many deserts get frost and even snow in winter, especially at higher elevations like the Great Basin and the Gobi.
- Is a desert defined by heat?
- No, by how little precipitation it gets, typically under about 10 inches a year. Antarctica is the largest desert on Earth.