However, none of the published studies indicate that tornadoes or hail produce green skies. A 1993 study from Penn State University argued that strong thunderstorms must be accompanied by substantial rainfall and the correct positioning of the Sun and thunderstorm to turn the sky green.

The author of the study, Dr. Craig Bohren and Dr. Alistair Fraser, offer two theories. Bohren suggests that sunlight behind a thunderstorm is weakened and scattered by rain and/or hail, resulting in a bluish hue. "If this thunderstorm occurs around sunrise or sunset, when the Sun appears more red/orange/yellow due to the longer path of sunlight through the atmosphere, the thunderstorm may appear greener," he explains.

"Ice rain is unlikely to produce a green sky, but the size of the droplets determines the exact green color. That is, smaller water droplets produce a blue-green or yellow-green sky," he said. According to Gallagher, it is possible that all thunderstorms have a greenish color at some point in their life cycle, but it is rarely seen at that time."