Why Does The Sky Turn Green Before Tornadoes?

In areas like the Central United States that get lots of tornadoes there’s a common piece of celestial fortune-telling. People say that green skies mean a tornado is on its way. Research has shown that it isn’t quite as simple as that, but scientists have found that if you see a green sky, you should probably go inside. As far as most scientists can tell, the green skies around powerful thunderstorms are usually a combination of red sunsets and water droplets. Like we’ve talked about before, daytime skies are blue because bluer shorter wavelengths of visible light tends to bounce off air molecules better than red longer wavelength light. So the blue light gets bounced all over the sky and looks like it’s coming from everywhere, meanwhile, around sunset sunlight travels through so much atmosphere that just about all the blue is bounced away from the horizon, leaving all those picturesque reds and oranges behind, but that quick summary hides something important. Sunsets might look exclusively red and orange, but there’s still some green and even blue light hidden in there, just far less than the other colors but for us to notice the residual green light, it needs to hit something that reflects green light much better than red. That’s where water comes in. Big tall threatening storm clouds are made of water droplets, and even though water is best at reflecting blue light, it can still reflect green pretty well, much better than reds and oranges, so under just the right conditions, the water in and around a cloud can bounce the green light hidden in the sunset right into our eyes making the sky look green. This explains why most of these eerie skies are reported late in the day when there’s not much blue light around to dominate. Of course, green skies can happen in the middle of the day too, enough blue light just has to get bounced elsewhere by the right combination of air molecules above the clouds and the water within them. Still, none of the conditions that can turn skies green are unique to the clouds that spawn tornadoes. They’re often associated with these twisters, because the intense storms that produce green tinted skies can also produce tornadoes, but they don’t always. Sometimes they just lead to lots of rain, and maybe some hail. So if you see huge storm clouds rolling in and a green tint in the sky, it doesn’t necessarily mean there’s about to be a tornado, but it does mean you should probably head indoors. Thanks for asking and thanks to all of our patrons on Patreon who help us keep answering questions like this. If you’d like to support the show or ask a question of your own you can go to patreon.com/scishow.

100 Replies to “Why Does The Sky Turn Green Before Tornadoes?

  1. We actually get green tinted sunsets not infrequently with summer storms in South Carolina, even if it's just a normal sized storm (hail is rare and tornadoes even rarer.) Never saw a green sky when I lived in Iowa though…

  2. Absolutely used this rule in southern Michigan area growing up. Didn't always mean a tornado, but it did mean a watch was gonna go up.

  3. Green skies don't necessarily means a tornado, but more of a hail threat. I think the reason why they're associated with tornadoes is because large hail can often accompany a tornado.

  4. Why don’t you make a video on the alternative theories about the Universe on YouTube this would be interesting and good for the YouTube community!!!

  5. I understand that not all green skies are tornadoes, but do all tornadoes (or all evening ones) turn skies green?
    If I understood correctly, the answer is no, and that makes it a very unreliable piece of "survival" info.
    Or as they say in Logic, it's an unnecessary and insufficient condition, also known as "null information"

  6. You get a putrid greenish yellow (big like grey poupon mustard) in the daytime here in Tornado Alley. I usually at least see a wall cloud or hear of a touchdown in a nearby town when the world turns that surreal color.

  7. Michael – I dont know how to say it but your hair is just so different now <.< I kinda miss the spiky look.

  8. I dont know about that! The green clouds must be chemtrails, but the government just blame the tornadoes just like they blamed Bin Laden.

  9. I'm from Oklahoma. Thunderstorms can have green light in mid days. It usually means that there is hail in the cloud. I have personally seen more than 20 tornadoes and survived 2. Very exciting and awesome thunderstorms here are.

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  11. I always wondered: How do people in those areas deal with having tornadoes so often? We in Germany rarely ever have tornadoes, and when it happens it does only little damage to people. When I hear about tornadoes destroying whole villages in the US (correct me if I'm wrong) I'm really not sure if I wouldn't just move away if was living there.

  12. Here on the east coast of Australia, once the summer storm clouds have built up, are swirling, & take on that greenish hue, there's a very good chance it'll be a severe thunderstorm with damaging hail, but only occasionally are there tornadoes & rarely as powerful as those that occur in your mid-western states!
    However, cyclones in Australia's top end are another matter, on par with your hurricanes (they just rotate the other way)!

  13. Why is it so hard to understand GOD works in mysterious ways? If the sky turns green don't ask, 'why' give thanks.

  14. I saw a green sky ONCE in my life (France Burgundy 1975) with the hell of a rain fall right after. I still remember it today…

  15. The meteorological equivalent to announcing unpleasant things that are about to happen and which will involve a lot of smashing.

    Except to me it doesn’t look green, it looks yellow.
    I always know it’s possible tornado weather if the sky is cloudy and the light is yellow.

  17. I've lived in Kansas for most of my life, a side from my time in the Army and being stationed in Georgia. Green has always signified hail but I've never heard it mean there will be tornadoes. I witnessed a tornado yesterday and then an hour later, witnessed green skies followed by hail. I've never heard green means a tornado until this video.

  18. this is the first time e-begging not only didnt piss me off but actually had somebenifit to the human race

  19. Also during that time, everything seems a much higher contrast. Like white buildings seem to stick out brightness wise far more than usual.

  20. Green clouds have been a sign for extreme hailstorms where i live (Germany). One Moment, the sky is dark green, without wind and ghostly silent, the next one its rain, hail and lightning everywhere, including floodings and destroyed trees and houses.

  21. We recently had a tornado outbreak in CT. The sky turned an eerie mint green, then about 10 minutes of intense lightning rain and hail and a sudden blast of wind strong enough to obscure the sky and now trees, then nothing. As if the world were coming to and end then complete calm except for the continued rain.
    We got 4 F0-1 tornadoes in Oxford, Beacon Falls, Southbury, Winsted, and a microburst in Danbury.

  22. After I first moved to Florida from Seattle, I drove through a storm that I later found out to be a confirmed F0 tornado. As I approached it, I noticed it being green and as I drove into it and it got dark, it looked more muddy green. I would analyze this to be from it pulling up grass and trees, instead of a water droplet thing. I stopped along the road until I could see a little and then continued on my way. Out the back side, it was blue skies and no rain. Strangest thing I had seen. I turned on the radio and found out there was a tornado spotted on the ground where I was. When I got home, the news showed the path it had taken. Confirmed tornado. I had expected to see one that looked like they do on Twister or other news. It did not look like that from my perspective.

  23. I saw the sky turning green one time while I was at evening church. It went from green to black and it was only 330 and there was a tornado warning. Don't go to church if there is a tornadic storm because they will sing about how they are ready to see God and how they aren't afraid to die. YALL ARE OLD OF COURSE YALL FEEL READY I HAVEN'T EVEN COMPLETED A FOURTH OF THE LIFE EXPECTANCY

  24. Living in Nebraska, I've always thought the green skys were really cool, especially just after a big storm when it's calm and smells like rain and the sun comes back and you remember that it's still like 4 pm

  25. Yeah, when the BLUE sky turns GREEN, hide. Like if the ocean leaves the beach, so should you. When something that is so regular and normal that we use it to indicate something regular and normal (i.e. the sky is blue) changes into something bizarre and otherworldly, that's Mother Nature telling you to hide.

  26. Occasionally I see a greenish sky but there are no tornadoes around here. It appears when it's really cloudy, so I always associated it with couds.

  27. In my atmospheric physics class we talked about this phenomena but it was attributed mostly towards the light interaction of suspended grapple or frozen precipitation on its way towards becoming hail stones unless they melt before hitting the ground.
    I've seen this phenomena (but not associated with tornadoes though I think some of the supercells in question did spawn them elsewhere, in general I had always thought it was mostly the powerful convection cell scattering away those wavelengths…

  28. I have a memory of my mom dragging me and my brother out of the basement where we were taking cover when we were very small to show us a green sky and tell us that its a sign of what my mom called a "serious business storm" and that when we saw it we were to ALWAYS take cover even if she wasn't there.

  29. I live in Louisiana and have seen a green sky once. It was FREAKY!!! The conditions were much as you described, late evening with a large incoming storm. Fortunately no tornadoes or hail, but it has been about five years and I still remember that eerie sky vividly.

  30. I've seen the skies get to be a demonic green-yellow color. Bad weather is imminent. Seek shelter, soon.

  31. Lived in Kansas myself for eight years and only incredibly dark clouds before a nasty thunderstorm, it was never really green. But we still had our fair share of close calls. But it's still cool that it's possible for a green sky right before a twister, kind of like a warning system from Mother Nature.

  32. Wrong. That green is not refraction, it is emission. The green is ionization radiation emitted in a local area. The ionization likely occurs from the wind turbulence and the wind need not be all that strong. Rain need not be present.

  33. I had a green sky in the middle of the day in West Texas. No tornados, but the storm left literal knee-high drifts of hail piled up against everything. You don't even have to know the folk meteorology. If you see a sky that looks greyish green and noon turns into dusk, no one has to tell you to go inside.

  34. I live in an area where tornados are not so easy to be created, but I did Basic and AIT in areas more prone to tornados, or tsunami and others. Had some safety tests on the tornado sirens at Fort Leonard Wood, but never had one happen while I was there. This is a nice, handy piece of information if I do end up seeing a green sky for my first time.

  35. I live in the UK and we're not known for having tornadoes here… but we do still occasionally get green-tinged skies late in the day. And it usually starts raining pretty soon afterwards. So I can see how they could be a sign of a potential tornado in some places!

  36. I'm from Kansas. I remember seeing this happen. It also reminds me of the storms in fallout 4

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