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Old 06-29-2010, 08:28 PM   #7
2nd Gear Member
Join Date: Jun 2010
Location: Canada
Posts: 172
Originally Posted by
Ask A Scientist©
Physics Archive

Radar Detectors and Weather

status other
age 30s

Question - Are police radar detectors affected by dense fog and or
rain? How and what are the affects.
Dear Rocket-

Your question about police radars and how weather affects them is a good
one. Weather has almost no effect on the operation of those radars.

What a radar "sees" depends on the character of the radar beam. In general,
the higher the frequency of the radar beam, the smaller the particles it can
detect. Radars designed to detect moving vehicles use frequencies that are
not reflected by small moisture droplets such as fog and clouds, or even

Very heavy rain can reduce the range of all radars, (an effect called
"attenuation"), due to the signal being absorbed by the precipitation. In
this case, weather conditions usually cause motorists to slow down to well
below the speed limit anyway.

Wendell Bechtold, Meteorologist
Forecaster, National Weather Service
Weather Forecast Office, St. Louis, MO
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