Green Skies

Thunderstorms are fairly common in the late spring and summer in the United States. Every once in a while, though, they can be severe. When they are, the sky often turns green. You may wonder, what causes this odd coloration?

According to scientists, the phenomenon of green skies is not completely understood. The leading theory, however, involves the dense moisture content of cumulonimbus clouds and the time of day. Most thunderstorms develop in the late afternoon, a time when the sun’s rays have to travel a long way through the atmosphere before reaching the ground. This causes the light we see around sunset to be reddish-yellow. Thunderstorm clouds contain large amounts of rain and hail. This water and ice scatters blue light. So, when these towering clouds form in the late afternoon, the two colors mix to give the sky a green or blue-green appearance.

While severe thunderstorms can produce tornadoes, a green sky does not necessarily mean a twister is coming. Nonetheless, the color is associated with dangerous weather. If you see a thunderstorm heading your direction and the sky appears green, you should seek shelter immediately.

Green Sky.  Image Credit: Sky7WX

Green Sky.   Image Credit: Sky7WX

This entry was posted in weather and tagged , , , , by Melissa Fleming. Bookmark the permalink.

About Melissa Fleming

Melissa Fleming is an environmental communicator and visual artist working at the intersection of art and science. She is passionate about exploring, learning, and sharing information about the natural world. She has presented her interdisciplinary work in a variety of mediums at venues and conferences around the world.