Tor Bergeron

Tor Bergeron was a Swedish meteorologist and a principal figure in the Bergen School of meteorology, a movement that introduced new conceptual foundations for understanding and forecasting weather in the early twentieth century. Bergeron is credited with discovering and describing the occlusion process, the final stage in the life cycle of a mid-latitude cyclone in which a fast-moving cold front catches up to and merges with a slower warm front. In the 1930s, working alongside German meteorologist Walter Findeisen, Bergeron developed what became known as the Bergeron process, the theory that precipitation in many clouds forms through the interaction of supercooled water droplets and ice crystals, in which water evaporating from the droplets accretes onto the ice crystals, which then grow large enough to fall as snow or, after melting, as rain. Bergeron received the Symons Gold Medal in 1949 and the International Meteorological Organization Prize in 1966 in recognition of his contributions to meteorology.