Aridity indexes are quantitative indicators of the degree of water deficiency present at a given location. A variety of aridity indexes have been formulated, although the term Aridity Index specifically refers to the 1948 work of Thornthwaite. Aridity indexes have been applied at continental and subcontinental levels and are most commonly related to distributions of natural vegetation and crops. Critical values of the indexes have been derived from observed vegetation boundaries. For instance, Classification Köppen, 1918 Köppen's 1918 classification defines the desert/steppe boundary as the 200-mm annual isohyet in regions where there is no seasonality of rainfall and the mean annual temperature is 5–10°C.
Formulation of aridity indexes is not straightforward due to the nature of aridity. First, aridity is a function of the interplay between rainfall, temperature, and evaporation. Use of mean annual rainfall as an index of aridity ignores the importance of temperature and evaporation....
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Budyko, M. I., 1951. O. Klimaticheskikh Factorakh Stoka (On climatic factors and runoff), Problemyfiz. Geog. 16, 41–48.
Dzerdeevskii, B. L., 1958. On some climatological problems and microclimatological studies of arid and semiarid regions in the U.S.S.R., in Climatology and Microclimatology: Proceedings of the Canberra Symposium. Paris: UNESCO, Arid Zone Research, pp. 315–323.
Hare, F. K., 1977. Climate and desertification, in Desertification: Its Causes and Consequences, Secretariat of the United Nations Conference on Desertification (ed.). Oxford: Pergamon Press, pp. 63–168.
International Crop's Research Institute for the Semi-Arid Tropics, 1980. Climatic Classification: A Consultants Meeting. Patancheru, India: IRCISAT.
Köppen, W., 1918. Klassification der Klimate nach Tempertur, Niederschlag and Jahreslauf, Petermanns Geog. Mitt. 64, 193–203, 243–248.
Köppen, W., 1936. Das Geographische System der Klimate, in Handbuch der Klimatologie, vol. 1, pt. C, W. Köppen and R. Geiger (eds.). Berlin: Gebrüder Bornträger.
Meigs, P., 1953. World Distribution of Arid and Semiarid Homoclimates. Arid Zone Programme vol. 1. Paris: UNESCO, pp. 203–210.
Meigs, P., 1960. Distribution of Arid Homoclimates: Eastern Hemisphere: Western Hemisphere. United Nations Maps No. 392 and No. 393 Revision 1. Paris: UNESCO.
Thornthwaite, C. W., 1931. The climates of North America, Geog. Rev. 21(3), 633–655.
Thornthwaite, C. W., 1948. An approach toward a rational classification of climate, Geog. Rev. 38(1), 55–94.
UNESCO, 1979. Map of the World Distribution of Arid Regions, MAB Tech. Note 7. Paris: UNESCO.
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© 1987 Van Nostrand Reinhold
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Stadler, S.J. (1987). Aridity indexes . In: Climatology. Encyclopedia of Earth Science. Springer, Boston, MA. https://doi.org/10.1007/0-387-30749-4_16
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DOI: https://doi.org/10.1007/0-387-30749-4_16
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