This photo of a supercell was taken in mid-August, 1997, in Fowlerville, Michigan. The supercell developed in about 30 minutes. This supercell moved in a southeasterly direction and eventually caused heavy downpours, lightning flashes, and small hail 20 miles away in Brighton, Michigan. The two humps of the cloud signify moist air rising.
Courtesy of Angie J Venturato