Why does the sky turn green before a tornado?

Answer 1

I have seen green thunderstorms (May 31, 1985) during a large-scale tornado outbreak. It is suggested that some of the nastiest thunderstorms have a green tint to them. However, not all thunderstorms/tornadoes have a green tint.

Dangerous thunderstorms that drop hail and produce tornadoes seem to be observed as turning green by the public and meteorologists, there may be a number of different reasons for the green color of storm clouds. It may be that thick, thunderstorm clouds, with their water vapor, rain and hail, scatter sunlight in such a way as to give the clouds a blue hue. When the sun is low in the sky, such as before sunset when most severe storms occur, the reddening light of the sun when shining through Earth's atmosphere makes the bluish cloud tint turn green. Or it may be that storm clouds act as a kind of canvas upon which low sunlight scattered by particles in the air paints a greenish color. These explanations may play in concert with each other to create the observed green tint.

Answer 2

To start, this does not always occur before a tornado, and sometimes it occurs without a tornado. Green sky is usually associated with severe storms, and hence possibly tornadic storms, but not always.
That being said, why the sky turns green is still the subject of scientific debate and research. The answer I have most often heard is that thick storm clouds filter the sun in such a way that green light scatters most efficiently, compared to a normal sky where aerosols scatter blue light most efficiently. One idea was that it was caused by the reflection of green foliage onto a storm, but this has been disproven. But again, I think the most widely used theory is that thick storm clouds filter the light, shifting it from the regular blue to a more blueish-green to green color.

Answer 3

There is no sickening color, there might be a green tint to the sky caused by the refraction of light off of hail which is common in the the large storms that can spawn tornadoes. Green is not always an indication of a tornado, it just means that there is probably some large hail in the storm and you should seek shelter and protect the windshield on your car.

Answer 4

Green tinges are often seen in severe thunderstorms and some people take it as a warning of hail but it can occur with very heavy rain, hail, snow or tornadoes - all of which are associated with severe thunderstorms.

As I understand it, the green is caused by the scattering of light by the supercooled water droplets in the cloud. Clouds with a great depth of supercooled water have a green tinge - and these are the very clouds likely to produce violent phenomena.

Answer 5

". . .One possibility is that thick, thunderstorm clouds, with their water vapor, rain and hail, scatter sunlight in such a way as to give the clouds a blue hue.

When the sun is low in the sky, such as before sunset when most severe storms occur, the reddening light of the sun when shining through Earth's atmosphere makes the bluish cloud tint turn green.

Or, maybe storm clouds act as a kind of canvas upon which low sunlight, scattered by particles in the air, paints a greenish color.

Both of these could be correct, and they may play in concert with each other to create the observed green tint. . . "

http://www.usatoday.com/weather/resources/basics/green-thunderstorms.htm