Koeppen, Wladimir Peter -
(1846-1940): Russian-German pioneer of climatology. Between 1900 and 1936 he developed a climate classification system based on temperature, rainfall and vegetation, the basic philosophy of which is still widely used today. This system distinguished five general climate types: tropical rainy, dry, warm temperate, cold forested, and polar. Modifications to these basic types were derived from seasonal information (i.e. climate with no dry periods, with a dry winter period, and with a dry summer period) and from general geography (i.e. steppe, desert, tundra, and perpetual frost).