The Köppen climate classification is one of the most widely used climate classification systems. It was developed by Wladimir Köppen, a Germanclimatologist, around 1900 (with several further modifications by himself, notably in 1918 and 1936). It is based on the concept that native vegetation is the best expression of climate, thus climate zone boundaries have been selected with vegetation distribution in mind.
Group D is microthermal or continental (hot/warm summers and cold winters) and subarctic (short warm summers and cold winters). The warmest months must have an average greater than 10° C and the coldest months must have an average of less than 0 or -3° C.
Group E is polar and alpine. The warmest month must have an average temperature less than 10° C.
↑Beck, Hylke E.; McVicar, Tim R.; Vergopolan, Noemi; Berg, Alexis; Lutsko, Nicholas J.; Dufour, Ambroise; Zeng, Zhenzhong; Jiang, Xin; van Dijk, Albert I. J. M.; Miralles, Diego G. (23 October 2023). "High-resolution (1 km) Köppen-Geiger maps for 1901–2099 based on constrained CMIP6 projections". Scientific Data. 10: 724. doi:10.1038/s41597-023-02549-6.
12345Harm J. De Blij; Peter O. Muller; Richard S. Williams Jr., Physical Geography: The Global Environment (New York: Oxford University Press, 2004), p. 71