Swedish meteorologist Tor Harold Percival Bergeron (1891–1977) formed the theory that is accepted today about how clouds formed, including the role that ice crystals, water vapor, and temperature play. His theories were later confirmed by German meteorologist Walter Findeisen (1909–1945). The process of cloud formation is therefore known as the Bergeron-Findeisen mechanism.
A bank of cumulus clouds hovers over the Atlantic Ocean near Deerfield Beach, Florida. (photo by Ralph F. Kresge, courtesy NOAA)