Just a couple of days ago I wrote about a story linking increased temperatures to derechos. And then yesterday the skies turned green (no, not with envy) as a derecho crossed the upper midwest and plains states. You can read about it here in The Washington Post.
From the story...
Ahead of the derecho, thousands witnessed skies turn an ominous shade of neon green, the heavens appearing borderline phosphorescent. While green skies are sometimes byproducts of thunderstorms, few meteorologists could remember having seen skies reflect that peculiar hue.
Winds reached 90 mph in places, that would make it equivalent to a high end Category 1 hurricane here on the coast.
Just how big is a derecho...
For a thunderstorm squall line to be classified a derecho, “damage must be incurred either continuously or intermittently over a swath of at least ~400 mi and a width of approximately ~60 mi) or more.” That’s according to the American Meteorological Society. The National Weather Service also stipulates that, in addition to widespread 60 mph winds, a few significant wind gusts, or those topping 75 mph, must be thrown in as well.
As for why the skies turned green...
The infamous green sky that comes with some severe thunderstorms has to do with what the thunderstorm is holding — water, and lots of it. It’s believed that big raindrops and hail scatter away all but the blue wavelengths, allowing primarily blue light to penetrate through and beneath the storm cloud.
Amazing and frightening.
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