South Dakota sky turns green. See the strange weather phenomenon in photos

SIOUX FALLS, S.D. — Before severe weather swept through South Dakota on Tuesday, residents around the city of Sioux Falls witnessed a hauntingly rare phenomenon: a green sky.

Yes, the sky was green. And not a light green –  the green that’s the color of the sky before Aliens arrive in a Jerry Bruckheimer movie. Or before the Wicked Witch of the West threatens Dorothy and her little dog, too.

The National Weather Service confirmed that a derecho barreled through much of South Dakota – as well as Minnesota and Iowa – on Tuesday, leaving thousands without power for hours after the “destructive,” long-lasting wind storm. As of Tuesday night, the extent of the damage from the storm was unclear as the storm and following warnings continued to stretch as far as Wisconsin, according to the NWS.

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In addition to heavy rain, the storm brought black, blue, grey and, again, murky green skies around southeastern South Dakota, including the Sioux Falls area. Weather watchers took to Twitter to share photos of the ominous sky, while we tried to find out what this green sky means.

Do green skies mean a tornado is on the way?

Green skies often come with severe weather, however that does not mean it’s a tornado specifically as there isn’t a direct correlation between the two, according to AccuWeather.

Why is the sky green in bad weather?

It’s not completely decided why green skies occur, the Scientific American reports. However, if a thunderstorm occurs during a time of red light, like a sunset, the water particles in the air can make it appear as if the sky is slightly green in color, some researchers say. The gray cloud of a thunderstorm, water particles that bend red light to appear blue and ample red light in the sky can create the perfect storm for a green sky.

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See the green sky photos in South Dakota

User Jaden (@jkarmill) caught the sky looking something akin to neon green.