Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Radar Detectors and Weather
Name: Unknown
Status: other
Age: 30s
Location: N/A
Country: N/A
Date: 1999 

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 precipitation.

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

Click here to return to the Physics Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory