Interesting spotting on radarMarch 8th, 2013 at 8:18 am by Nicholas Ferreri under Weather
Here’s an interesting radar spotting that comes from the National Weather Service – Chicago Office.
The National Weather Service says the long, narrow returns that show up in the animation are from chaff being dispersed by aircraft. According the the National Weather Service in Louisville, where similar images have been spotted, chaff commonly is in the form of very small pieces of metal, like aluminum.
Chaff is said to typically be used by the military as a way of counteracting radar during military measures and to throw off an enemy. Basically, with the metal pieces being released, the radar beam encounters them in the atmosphere and the beam is then reflected back toward the radar site – just as it would be when encountering actual raindrops.
The NWS in Chicago did not list a reason as to why chaff was being used by the military when it showed up on radar Thursday evening.