Aliens? Surface of the ground? Hail?
How aboutâ€¦none of the above (except maybe aliens).
The answer actually lies within a simple trick of light. Storm clouds are inherently blue and sunlight tends to be orange or red â€” put those two colors together and you end up with green of some sort.
So not magic. Not a refraction of ice â€” just good old fashioned tricks of light.
Hereâ€™s the full explanationâ€¦