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© NOAA
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Norman Doppler Radar installation.
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Radar (radio detection and ranging) has become an important tool for
observing and predicting the weather. Radar was invented and developed
in Britain and the U.S. at the beginning of the Second World War. It was
used to detect the approach of enemy airplanes. An antenna sends out radio
waves. The waves are reflected from solids or liquids in the air and received
back by the antenna. The radar equipment shows the position and distance
of the objects. The results are shown on a screen. The screen is similar
to the screen of a television or a computer monitor. Weather radar can
show the locations of areas of precipitation very clearly. The radar images
are also able to show the intensity of the precipitation.
Satellites were first put into orbit in the 1970s. Satellites with cameras
have been used to get images of the Earth's weather from space. Satellites
are especially good at showing cloud cover. Photographs of cloud cover
are not the only advantages of satellites. Special instruments are mounted
on the satellites. They can measure the temperature of the Earth's surface.
The most useful satellites are ones with orbits adjusted so that the speed
of the satellite is the same as the speed of rotation of the Earth. Then
the satellite stays in the same place overhead.
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