Severe thunderstorms containing hail can exhibit a characteristic green coloration Frank W. Gallagher, III. (October 2000). “Distant Green Thunderstorms – Frazer’s Theory Revisited”. Journal of Applied Meteorology (American Meteorological Society) 39 (10) : 1754. Bibcode 2000JApMe..39.1754G. doi:10.1175/1520-0450-39.10.1754. (Photo credit: Wikipedia)