Why does the sky sometimes turn green during thunderstorms?
If thunderstorm cloud tops are cold enough, severe thunderstorms can produce hail that is over three-quarters of an inch in diameter or larger. Scenes of skies turning colors can be common during large derecho events, especially over the heartland.
Have you ever found yourself close to a storm, and the skies appear to turn a sudden shade of green? Well, NOAA meteorologists believe they might know the answer behind this stunning light display.
According to the agency, a common belief is that ice in storms helps to scatter light, making the cumulonimbus clouds appear as if they are a different color.
It is common for thunderstorms to produce hail, but only a few go on to reach severe warning status, with hailstones that are larger than three-quarters of an inch in diameter.
The more hail and rain that is in a storm cloud, the more likely a strong updraft is in play, helping to scatter light and making the sky appear green.
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The events are mostly known to occur during the evening and early mornings when the sun is at a low angle on the horizon.
According to National Weather Service meteorologists, water and ice particles inside the clouds work to scatter the blue light. When the light is illuminated by the sun’s rays, it can appear to have a greenish tint.
"Water/ice particles in storm clouds with substantial depth and water content will primarily scatter blue light," officials at the NWS office Hastings, Nebraska. "When the reddish light scattered by the atmosphere illuminates the blue water/ice droplets in the cloud, they will appear to glow green."
Common producers of these events include severe thunderstorms and derechos.
A derecho is a cluster of storms that produces destructive wind gusts and hail for hundreds of miles and has the potential to impact millions of people.
A July 2022 derecho event that moved through the Northern Plains produced hail, damaging winds and an eerie shade of green in the sky.
Department of Transportation cameras in Sioux Falls, South Dakota, captured the stunning imagery that almost made the landscape look like it was dyed.
In addition to the heavy rainfall, golf-ball to tennis-ball-size hail was reported during the severe weather event.
There is no known correlation between a blue-green sky and tornado production. Green skies do not guarantee a tornado will form from the clouds, but the color does likely indicate the storm is capable of a common sight during supercells – large hail.