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A Weird Blob Over Alabama Turns Out to Be a Military Test

The stationary “cloud" was a controlled release of something called chaff.

On Wednesday afternoon weather radars detected a cloud near Huntsville, Alabama, hovering in place for hours. Its lethargy was odd, as was its existence, because the day was clear.

Was a microstorm absolutely raining buckets on a few unlucky families? The explanation might be just as weird for those who aren’t into military technology. Radars were actually picking up on a plume of chaff released over Redstone Arsenal, a large Army installation in northwest Alabama. When it fell to the ground, the stuff resembled little wads of metallic fluff, like steel-wool snowflakes.

Here’s the purpose of chaff, according to GlobalSecurity:

When ejected from an aircraft, chaff forms the electromagnetic equivalent of a visual smoke screen that temporarily hides the aircraft from radar. Chaff also serves to decoy radar allowing aircraft to maneuver or egress from the area. It consists of small... fibers of aluminum or aluminum-coated glass that disperse widely in the air when ejected from the aircraft and effectively reflect radar signals in various bands, in order to create a very large image of reflected signals (“return”) on the radar screen. In the air, the initial burst from a chaff bundle forms a sphere that shows up on radar screens as an electronic cloud. The aircraft is obscured by the cloud, which confuses enemy radar.

The arsenal later confirmed it dispersed chaff as part of “threat countermeasure testing,” reports WHNT News, so all you Alabamans fearing an invasion can put down your guns now.

About the Author

  • John Metcalfe
    John Metcalfe is CityLab’s Bay Area bureau chief, based in Oakland. His coverage focuses on climate change and the science of cities.