Why the sky can sometimes appear green when storms are near

We are all wearing green today for St. Patrick's Day, but if you look at the horizon and see the sky wearing green, it's not a celebration; it's a warning. When we see that eerie emerald glow during a Missouri storm, many call it 'tornado weather'. But the science behind the shade actually points to something much more solid.

This more solid feature is hail, and this phenomenon most commonly occurs during the day. This is all because of the angle of the sun during the afternoon before it sets. As the light rays from the sun enter the Earth's atmosphere and pass through the cumulonimbus clouds that contain hail, the hailstones and water droplets scatter the light rays. This causes the warmer colors, like red and orange, to remain in the upper levels of the atmosphere, while the cooler colors, like greens and blues, pass through the rest of the cloud and move closer to the surface. Depending on where you are in relation to the storm and the sun, you might notice a greenish hue under the most intense areas of precipitation because of the hailstones. This is the same reason why if you are on the sunny side of a storm, you may see a rainbow. The sun rays are scattering the raindrops and hailstones in front of you, and you get to see the visual of all the colors on the spectrum getting dispersed through the precipitation and then reflected to cause the formation.

The size of hailstones can also change the type of color that you see under the storm. For larger hailstones, the color range is closer to a green-yellow mix, while smaller hailstones and areas of heavier rainfall contain more of a blue-green mix. This means that if you see a storm that almost seems like a green or yellow light emitting from it, that storm is producing very large hailstones. With any of these storms, tornadoes can still be present or possible, especially when larger hailstones are being produced. These storms are in better environments for stronger storms to occur, so even though the hail is the main reason why the sky looks so different, the threat of tornadoes is just as likely.

St. Patrick's Day history in Columbia, Missouri, is just as colorful. We've seen everything from an 83-degree spring fever in 1894 to being buried under 13 inches of snow back in 1960. Today, we aren't seeing any storm threat and, in turn, no potential green sky. Still, with temperatures over 15 degrees below average and a chance of flurries, we're reminded that in Missouri, March is always a wildcard.

This March madness is expected to continue, as a ridge, otherwise known as a large area of high pressure, is expected to move into the region. This means that settled weather, sunshine, and warm southerly winds will be taking over. This will lead to temperatures jumping into the 60s and 70s by the middle of the week, then potentially bringing temperatures closer to 80 degrees by the end of the week.