Radar senses smoke plume from big Chicago fire

January 23rd, 2013 at 1:00 pm by under Weather

This Chicago radar image depicts a smoke plume from a large Chicago fire. (Image captured 10 PM 1/22/13 – Image Credit: National Weather Service Chicago)

On Tuesday night, the smoke plume from one of the biggest fires in Chicago in years was able to be spotted on Doppler radar.  You may wonder how this happens because, after all, isn’t radar looking for rain and not smoke?  The reality is the pulses of energy being emitted from the radar are simply looking for “targets” in the atmosphere.  Most of the time, these “targets” are raindrops or hailstones.  Sometimes, though, they can be birds, insects, wind turbines or smoke particles from fires.

Once the radar beam encounters these targets, it bounces back to the radar dome where the radar computer calculates the location of the target (based on how long it took for the radar beam to bounce back) and its intensity is determined by the amount of energy that comes back to the radar.

Now if we didn’t know there was an actual fire occurring, could meteorologists still determine this was a smoke plume on radar and not rain?  The answer is yes and it would be determined most easily by looking at a loop of radar images over time.  What we’d see with a smoke plume is a stretched out, nearly stationary radar pattern extending from a single location, the origin of the fire.  Areas of rain gradually move over time and do not have the same nearly stationary pattern or stretched out shape as a smoke plume.

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