Why is there a difference in temperatures of day and night in the desert?

Answer 1

Sand does not retain heat, so during the day the sun heats the sand rapidly, and it cools rapidly at night.

Clarification:

Deserts generally lack clouds and humidity which act as a blanket to hold in the daytime heat. Once the sun sets the heat radiates back into space.

Answer 2

Not all deserts are hot, the Gobi is a cold desert. It is the lack of free water in soil and air that defines desert, the Antarctic is a desert.

But back to hot deserts. It is the lack of water in the soil that makes it hot. If there was moisture in the soil, much of the suns heat would go into evaporation of it, evaporation "absorbs" heat. Plants also increase evaporation as part of photosynthesis. There are few plants in deserts and the ones that are there have various ways of preventing evaporation.

The lack of water is also why deserts get cold at night. Dry ground does not hold as much heat as moist ground. Water, as vapor in the air, or visible clouds, acts as a blanket to prevent heat from the ground from radiating out into space. In fact water vapor is the single most important green-house gas.

Sun shining on bare sand does not make deserts hot. Sandy deserts may feel hotter because sunlight reflects off it. Just as standing in sun on a beach feels hotter than standing in shade, though the air temperature is the same. But reflecting actually makes the sand cooler. Reflected heat is unabsorbed heat. Dark colored plants absorb more heat than sand, if there was some sort of no-water plant in deserts, the desert would be even hotter. There are some dark sand deserts that are hotter in day than light colored sand ones because the absorb and hold more heat.

Answer 3

There are no deserts that are very hot during the day and below zero at night. Hot deserts may cool to the 50s and 60s F at night but only the cold winter deserts, such as the Gobi or Great Basin Deserts will drop below zero and only in the winter. The Antarctic Desert is perpetually cold and only a few areas along the coast will ever get above the freezing point, even in the summer.

Answer 4

The desert has few clouds and humidity which help slow heating during the day and permit the heat absorbed during the day to rapidly radiated back into space at night.

Answer 5

That depends on the particular desert and season of the year.