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Scientific reasons behind that eerie yellow sky (that have nothing to do with the apocalypse)
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You glance outside on a perfectly normal afternoon and notice the sky is glowing an eerie yellow—but why? A yellow sky can definitely look ominous, but don't worry, there's a perfectly logical explanation for that unusual yellowish tint. In this article, we'll explain exactly what's happening when it looks yellow outside and discuss all the possible scenarios that can create this effect in our sky.

Things You Should Know

  • The most common cause of a yellow sky is storm clouds. The clouds scatter the blue light coming from the sun, and this makes the light look yellow to us.
  • Dust storms, pollen, and smoke in the atmosphere can also cause it to look yellow outside for the same reason: they scatter the blue light in the sky.
  • A yellow sky doesn't necessarily mean a tornado or hurricane is on the way. Any kind of storm cloud can cause the sky to look yellowish (or even greenish).
Section 1 of 3:

Possible Causes of a Yellow Sky

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  1. A brewing storm (especially a late afternoon storm) is the most common reason for that eerie yellow cast that sometimes happens outside. The clouds scatter the short wavelengths of blue light that come from the sun, and when that scattered light is projected into the sky, it can look yellowish from our perspective here on earth.[1]
    • When the clouds themselves look yellow, it's most likely due to the molecules of water inside of them. The molecules are blue, so when the light reflects off them and scatters, the clouds can look yellowish.[2]
  2. Scattered blue light is to blame, but in this case, the scattering is caused by the sun being low on the horizon. When the sun is low, the light passes through more air than it does during the day (when the sun is high in the sky). Natural molecules in the atmosphere scatter the violet and blue light away from our eyes, resulting in those gorgeous sunrise/sunset hues: yellow, orange, and red.[3]
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  3. It’s strange to think that dust from a faraway place can influence the way the sky looks where you are, but it happens occasionally. In 2017, dust from the Sahara desert was blasted into the atmosphere due to a strong storm that swept across Europe. All that dust and moisture scattered the blue light in the sky over the United Kingdom, making it glow a deep yellow color.[4]
  4. High winds during peak pollen season can whip large amounts of pollen high up into the sky, scattering the blue light rays until everything looks yellowish. The pollen is usually yellow, as well, which makes the color even more vivid. An incident like this occurred in May 2022 in the Boston, Massachusetts area.[5]
  5. Just like with the storm clouds and dust, smoke in the atmosphere can scatter the normal blue light until the sky turns a smoggy yellow color. It takes quite a lot of smoke for this to happen, so this scenario is pretty rare—it usually happens during extremely large wildfires (like the ones that tend to occur in California and along the West Coast).[6]
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Section 2 of 3:

Does a yellow sky mean a tornado is coming?

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  1. A yellow sky usually just means a thunderstorm storm is brewing. Storm clouds can scatter the normal blue light in the sky, which sometimes creates a creepy yellow or even greenish glow (especially late afternoon storms when the sun is lower on the horizon).[7]
    • A yellow or greenish sky also doesn't mean a hurricane is coming. In most cases, if you see dark clouds, you can expect a regular thunderstorm.
    • Thunderstorms are usually pretty safe as long as you take shelter, but it never hurts to be prepared for severe weather.
Section 3 of 3:

Does it mean something bad when it's yellow outside?

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  1. Despite the perfectly reasonable scientific explanations, this phenomenon is actually quite rare. And since we’re very accustomed to our serene blue sky, that yellowish hue can look a bit haunting and unnatural. No matter what anyone says, though, the world isn't about to end and extreme weather is not necessarily imminent.
    • Check local weather reports and recent news stories for clues. If local meteorologists are expecting storms, or if you run across a news article about sand storms, wildfires, or extreme pollen, you'll know for sure what's happening.
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About This Article

Amber Crain
Co-authored by:
wikiHow Staff Writer
This article was co-authored by wikiHow staff writer, Amber Crain. Amber Crain has been a member of wikiHow’s writing staff for the last six years. She graduated from the University of Houston where she majored in Classical Studies and minored in Painting. Before coming to wikiHow, she worked in a variety of industries including marketing, education, and music journalism. She's been a radio DJ for 10+ years and currently DJs a biweekly music program on the award-winning internet radio station DKFM. Her work at wikiHow supports her lifelong passion for learning and her belief that knowledge belongs to anyone who desires to seek it. This article has been viewed 52,709 times.
23 votes - 82%
Co-authors: 6
Updated: December 6, 2024
Views: 52,709
Categories: Yard and Outdoors
Thanks to all authors for creating a page that has been read 52,709 times.

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