Q: Why does the sky sometimes look green during a thunderstorm?
A: Itâ€™s a question that has been asked for centuries and is still not fully answered, says Brent McRoberts of Texas A&M University. “We know the ancient Greeks reported seeing green skies during thunderstorms, and sailors for hundreds of years have written about green skies,â€ McRoberts explains. “The most popular theory is that thunderstorms contain a lot of water â€“ often in the form of hail â€“ and this water or ice tends to scatter green light during the strong updrafts that occur in severe storms. Thatâ€™s why many people say the sky appears green right before a hailstorm.â€
Q: Does the sky look green during a tornado?
A: It can, says McRoberts, but not always so. “Often the sky appears almost black during a tornado, but sometimes there are greenish-looking tints to the clouds,â€ he adds. “Many tornadoes have hail right around them. What we do know for sure is that green skies do exist, but they are fairly rare. They may or may not contain a tornado, and they may or may not contain hail. We do know that they are almost always an indicator of severe weather, often very dangerous weather, so if you see a thunderstorm approaching and the sky appears to look green, you should take cover immediately.â€