Photograph of cumulus clouds in the mountains of Colorado.
Click on image for full size
Courtesy of Lisa Gardiner
Clouds
Clouds can come in all sizes and shapes, and can form near the ground or high
in the atmosphere. Clouds are groups of tiny water
droplets or ice crystals in the sky and are formed by different processes. They can produce different kinds
of precipitation dependent on the atmosphere's temperature.
Cloud types are classified by height and
appearance. The shape depends on the way the air moves around the cloud. If air moves
horizontally, clouds form in spread-out layers. However, clouds grow upward if air movement
is vertical. Clouds reach higher heights near the equator and develop at lower heights near
the poles.
At any given time, clouds cover about 50% of the Earth. We would not have rain, thunderstorms,
rainbows, or snow without clouds. Clouds make up some of the atmospheric optics we can see in the sky. The
atmosphere would be quite boring if the sky was always clear!
Did you know that Earth is not the only planet with clouds? Other planets, like
Venus,
Mars,
Jupiter,
Neptune,
Uranus, and
Saturn, have clouds too!
Shop Windows to the Universe Science Store!
The
Fall 2009 issue of The Earth Scientist, which includes articles on student research into building design for earthquakes and a classroom lab on the composition of the Earth’s ancient atmosphere, is available in our
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