Why desert nights are cold and days are hot?

Answer 1

Deserts are dry so they have no cloud cover.

• During the day the sun heats up the land.
• At night there are no clouds to stop the heat escaping so it all rises up and escapes into space.

During the day the sun burns up and the sand soaks up the heat causing a oven effect.

While at night the wind will blow, and the sun is gone so the effect is like garages in the night.

The desert has very low humidity levels and little cloud cover. In most biomes these two factors act as blankets to hold in daytime heating, In the desert, however, these two factors are usually absent and the heat radiates back into space once the sun sets.

Desert is so hot during the day because there are no water vapors in the air that serve as reflectors of the heat of the sun, these vapors also trap some of the sunlight from entering the earth surface, so without them the heat is so intense. At night the desert is so cold, since there are are no water vapors in the air that serve as traps, the heat of the sun that supposed to keep the area warm at night can easily escape into the atmosphere leaving it so cold.

The primary difference has to do with the lack of moisture, both in the air and at the surface.

During the day, the sky tends to be clear so all of the sun's direct radiation is able to reach the surface. Furthermore, almost all of the radiation is able to directly heat the surface because it is so dry. It is also efficiently absorbed by the sand and rocks, since there is little living ground cover. Compare that to the ocean, where a lot of energy instead goes toward evaporating the water. Or even the rain forest, where there is so much wet vegetation that much more solar radiation goes into evaporation and transpiration.

At night, there is no incoming solar radiation of course. The reason it gets cooler at night (anywhere) is because the Earth emits radiation (it emits it during the day as well, but this is compensated by incoming radiation) back out to space. There tends to not be any clouds at night in the desert either, which allows all of the radiation to go back out to space rather than get trapped near the surface. This is the primary reason that it can get quite cool at night. Water vapor in the air acts in the same way as clouds do, and since there isn't much of that either, the atmosphere has even less ability to retain heat.

A: Because desert air contains less moisture and because cloud cover is less frequent in deserts, temperatures vary more widely between day and night in deserts than in other areas. However, it is a myth that desert nights are typically cold after hot days. Even though deserts may experience temperature variations of 30-40 degrees between day and night (vs 20-30 degrees in other areas), this means a nighttime low of 70-80 degrees after a 110 degree day - hardly what anyone would consider frosty. And in urban areas in deserts, there is even less variation between daytime and nighttime temperatures (thus the hot summer nights in such places as Phoenix or Las Vegas). But even in unpopulated or lightly populated areas such as Death Valley or Yuma, you are in little danger of freezing (or, for that matter, NOT needing an air conditioner) on a typical summer night.

Answer 2

The desert has very low humidity levels and little cloud cover. In most biomes these two factors act as blankets to hold in daytime heating, In the desert, however, these two factors are usually absent and the heat radiates back into space once the sun sets.