Why is it really hot at a desert in the day time and really cold at night?

Question

I've studied this many many times and my Dad says it has to do with the low humidity but my real question is: like in pictures of the desert, the sun looks big and really close and the moon also looks big and really close... how can the moon and sun be closer to a desert when the earth is even (no part is closer to the planets than the others). Sry for such a confusing question I just want to know...

plus, how are there storms over a desert when there is no water around to evaporate and cause a storm to form? I know it didn't develope OVER the desert, but how could it stay together with no moisture in the air?

Thx 10 pts =)

Answer 1

Your dad is right. Low humidity allows the heat to escape easier into the upper atmosphere, which allows the heat to drop quickly at night. The low humidity also allows the suns light to heat up the ground more quickly during the daytime.

The pictures are taken at times to maximize the size of the sun and moon, to make them look bigger than they really are in comparison to normal. You are right in saying that the moon and sun are not closer to the desert than the other parts of the earth are. You can take pictures of the moon and sun on any part of the earth earlier or later in the day and it will appear larger because the light has to travel further through the atmosphere and the light gets scattered more by the atmosphere, therefore it looks larger.

The storms that travel over the desert get their water from the oceans and the Gulf of Mexico primarily. There is enough moisture in these storms that they can continue over the desert without being dissipated.

Answer 2

Clouds have an insulating effect. Lack of cloud cover allows heat to escape. I have sometimes heard that mentioned on our local news weather report. On a clear day, the meteorologist mentioned that the night was going to be colder than usual due to the lack of clouds.

Also, the very dry soil loses heat very quickly when the sun goes down. (Water is an excellent capacitor of heat - meaning that it holds heat energy and releases it slowly)

As for storms, their is always moisture in the air everywhere. Even in the driest part of a huge desert, the humidity level doesn't get below 15%.

Answer 3

It's really not a difficult question . Things look closer in the desert both day and night because all you have to look at is sand so you are looking at the skyline all the time and it looks closer , kije when you go to the beach and start to the water, it seems closer than it is because you are looking directly at the water no trees or any other vegetation.

Your secon question about why it so hot at night and so cold during the day . In the day your dad is toatally correct , it is the humidity ,

At night now it only feels cold , the temperature is really not cold . In Viet Nam I slept under a blanket at night yet during the day We could not ever get cool. You see in the day it would be like 120 degrees outside and at night it would be like 80 or 85 degrees . A 35 to 40 degree swing will make you feel cold .

Lastly the rains hold together because teven though there is no or little moisture on the groud , in the upper airstreams there is moisture and that holds it together . However sometimes the upper airstream is moist enough to hold it together and it rains , but never gets to the ground.

I hope this answers it for you if not just sing out and I will try to make it clearer

Answer 4

The main reason for the hot days and cold nights in deserts is the lack of cloud cover, which is due to low humidity.

Clear skies let the sunlight in to heat the ground and air during the day.

Clear skies at night let the heat radiate out quickly.

Water, even as a true gas, has a tremendous capacity for holding onto heat.  Without the clouds the transfer o heat is quicker and stronger.

Your  father was right.

The moon and sun appear closer partly because of the greater clarity in dry desert air.  And partly because of perspective, without objects nearby to give an idea of scale solitary objects look bigger.

The reason storms are so dramatic over deserts is because of the contrast of humidity and temperature when  storm body moves in  It can't "stay together" long.  The sudden storm is how the storm comes apart.  If the differences between temperature and humidity were less the storm would lose its water and energy more slowly, less dramatically.

Answer 5

A desert is an area that's very, very dry--it isn't defined by being hot or cold, and it can be either.

The Atacama desert of Chile is a very high plateau that is pretty cold most of the time.

Believe it or not, Antarctica is a kind of desert, and you know that it is cold.

Here's a list of the world's big deserts: http://en.wikipedia.org/wiki/List_of_des...

But, I think that you are talking about deserts like the Sahara, Arabian or the Mojave deserts. These often do get really hot at certain times of year, but may cool off at night. I believe that your Dad is correct that the low humidity helps the earth's heat to radiate away at night.

The Sahara desert can have severe rainfall, though it may be years between storms. I know that there are rainstorms over the Mojave desert sometimes, and they can cause flash floods.

The pictures that you see of the desert may have been taken with a camera lens that  makes the sun or moon seem close. Photographers pick their lenses to make the most impressive and memorable photos--not necessarily to make the most realistic photos.  Also, when the sun or moon are close to the horizon, our brains interpret them as bigger than they seem when high in the sky.