Chaff Showing up on Radar

If you happened to check the radar today, you probably were wondering why there were returns on it while skies were completely clear.  Well, radar picks up on a lot of objects besides precipitation, and in this case it is chaff.  Chaff is a countermeasure used by military jets consisting of very small pieces of aluminum.  Winds at this level (about 4kft off the ground) were out of the north-northwest, so that is why the general motion of the bands are to the south-southeast.  They appear in bands because they follow along the path that the jet is taking.  With the recent dual polarization upgrade of National Weather Service doppler radars, we can tell that these are not precipitation returns based on the low correlation coefficient (right animation). For more information on this subject, please refer to the following web page: http://www.srh.noaa.gov/mfl/?n=chaffdualpol
Chaff Reflectivity-January 23, 2014 Chaff-Correlation Coefficient


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