Question about the desert?

Question

How come there is such a big difference between the temperature of the desert during the day and during the night? One of my friends says it has something to do with the clouds, they absorb light and radiation or something, but I didn't really understand her explanation.

Can someone answer, please?

B.

Answer 1

When we say that something is "losing heat" the way that it does so (or one of the main ways, at least) is by giving off infrared light - a wavelength that we cannot see but that we can detect easily - it is the reason that direct sunlight and heat lamps "feel warm". As objects absorb infrared, they warm. As they give off infrared, they cool. As the ground gives off infrared radiation at night, it cools.

Clouds do two things - they trap some of the infrared radiation, and they reflect some of it. The trapped infrared actually heats the air that contains the clouds, putting a heated blanket around the ground and slowing its cooling. The reflected infrared going back down to the ground is like putting the ground under a heat lamp, and giving it some of the energy back. These two effects dramatically slow the cooling process. In contrast, all of the radiation that hits a cloudless sky is lost, and the ground cools more quickly.

A secondary effect comes from the heat-holding capacity of the ground itself. Water holds a huge amount of heat. It takes two to three times as much energy to heat water (or water-containing substances such as vegetation) relative to the amount of energy required to heat the same mass of rock. Desert areas tend to have a lot of rock, and very little water or vegetation. The ground actually contains less heat, so that when it starts to lose energy at night there is less to lose and the ground cools faster.

Answer 2

Yes;it is due to the absence of clouds over the deserts almost throughout the year.A detailed explanation follows.
Clouds are good reflectors of solar radiation,only a small amount being absorbed by them.Therefore ,when the sky is cloudy,major part of the incoming solar radiation is obstructed from meeting the earth's surface due to reflection,the small amount which is absorbed raising the temperature of the cloud only.If now,the temperature of the surface is lower than that of the cloud,the cloud will emit radiation in terms of long waves which will again be reflected by the earth and this portion of radiation will thus remain almost confined in between the earth and the cloud.
As a result,clouds will tend to smooth out the diurnal variation of temperature by keeping the temperature low by day and comparatively high at night.
This will not happen on days with clear sky.As the deserts have clear sky always,the temperature shoots up during day time and in the night all the heat received escapes into space as there is no cloud to prevent the heat from escaping which leads to very colder night.

Answer 3

Clouds act as a 'blanket'. During the day they are reflecting the solar radiation back up into the atmosphere and at night they are holding in the energy received during the day. They tend to 'smooth out' the temperature variations.

Without the clouds the blistering 118 degrees you get during the day will radiate back out and the night will cool off by up to 30 degrees. I live in Las Vegas and never thought 90 deg. could be so cool!!!

Answer 4

The above answers are correct. However, the general belief that deserts have "hot days and cold nights" is a misconception. Only some high deserts come close, because of the thin air, and the days aren't really hot but just warm.

If the high is 120, a low of 80 degrees is still pretty hot, despite the large difference.

Answer 5

Deserts have little vegetation like plants to help keep the land warm up.

They neither have trees to shade the soil from total heat.

Answer 6

cloud less days allow quick heating
cloud less night allow quick cooling of the days heat build up