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Desert Temperature Extremes
Name: Tyra
Status: student
Grade: 4-5
Location: GA
Country: N/A
Date: 10/31/2005
Question:
Why is it so hot in the daytime in deserts and so cold at
night?
Replies:
The sky above a desert is usually very clear. So during the day the ground
absorbs most of the sunlight that strikes it -- heating the surrounding
air. At night the reverse happens. The hot ground (and air) radiate the
heat absorbed during the day back into space causing the temperature to
drop rather rapidly. So it is all about converting visible radiation into
heat (infrared radiation) and re-radiating that back into space.
Vince Calder
Dear Tyra-
The main reason there are such big temperature differences between day and
night in the desert is there is very little moisture in the air in the
deserts. We measure the moisture in the air with a number called "relative
humidity."
Moisture in the air "holds" the heat, much like a blanket over you holds
your body heat when you sleep. So, places like islands in the tropics, or
in jungles, where there is lots of moisture in the air, have small
differences between daytime and nighttime temperatures. These differences in
weather conditions, like desert weather and jungle weather are called
"climate." The jungle climate is much different from a desert climate.
Wendell D. Bechtold, Meteorologist
Forecaster, National Weather Service
Weather Forecast Office, St. Louis, MO
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Update: June 2012
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