“Why do tornadoes turn the sky green?”

Image by James Stutzman, via Flickr

When I was a wee sprout, I heard from someone in Tornado Alley that you only have to worry that a tornado is coming if the sky turns green. I shared this little factoid with our daughter in one of our many recent conversations about tornadoes, and was rewarded with the inevitable question.

“Why do tornadoes turn the sky green, Mommyo?”

I didn’t know. Naturally. I never seem to know. But I have an iPhone. So we asked it.

According to this article in Scientific American, it turns out there’s no proven link between green skies and tornadoes (or hailstorms) at all. Yeah, the sky sometimes turns green when there’s a thunderstorm pending, but hailstorms and tornadoes aren’t terribly picky about sky color. They are happy to pop up whether the sky is green or a more typical stormy grey-blue. Pretty much the only thing you can count on is that the sky will be dark when that tornado drops by.

So if the green sky isn’t the result of the tornado, why does the sky turn green during severe storms?

Research on green thunderstorms is apparently prone to being called out as a waste of money by members of Congress not from Tornado Alley, making it both woefully underfunded and rather hazardous to your meteorological career. Until that situation changes, we may have to make do with scientific speculation. Current thinking is that the water particles in the air change the color of the sky. The water particles absorb red light, making the remaining light appear more blue. Scattering that blue light across a red sunset and a dark grey cloud can make the sky look faintly green. Which explains why most green thunderstorms are spotted in the late afternoon and evening.

One comment

What are you thinking?

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.