enter image description hereCan anyone explain these strange rays? They seem to be pulsing in roughly the same location when you watch the radar and are always in the same circle pattern. Thanks for your input!

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    $\begingroup$ What is the source of the picture? Is it a weather service radar image for rainfall or is it an airport radar image? The rays appear to have three sources: Toronto, Smiths Falls & Montreal. $\endgroup$
    – Fred
    Jun 26 at 18:49
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    $\begingroup$ These are usually the result of RF interference occurring when the radar was sampling in the direction of the rays. Doesn't mean the interference was in the direction of the rays however, just where the radar was "looking" when it occurred. $\endgroup$ Jun 26 at 20:48

1 Answer 1


These appear to bursts of electromagnetic interferences (EMI). The rays are all centered on the location of the weather radars. As the weather radars rotate and receive interference they interpret it as a weather return in the direction they are pointing in at the time the interference signal is received. As these radars have no additional means of determining the direction of arrival of the signals we see these "spokes." The sources of this interference, which is EM radiation at the same wavelength of the radar, is typically from spillover from telecommunication equipment or other radars using in similar wavelengths.

Similar patterns can be seen is this image:

Uncorrected horizontal reflectivity Zh acquired by Bric della Croce radar in 2010

This figure is from Survey on Electromagnetic Interference in Weather Radars in Northwestern Italy,a paper studying the impact of interference on weather radar.


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