The air as a water absorbing medium

  • C. W. Thornthwaite
Part of the Handbuch der Pflanzenphysiologie / Encyclopedia of Plant Physiology book series (532, volume 3)


Water bodies cover more than four-fifths of the surface of the earth. Water is present as soil moisture and as liquid in plant tissue over most of the remainder of the earth’s surface. Water vapor is present in varying concentration everywhere in the lower atmosphere. The molecules that make up the water on the earth’s surface and the water vapor in the atmosphere are in ceaseless motion. Some of the molecules of the liquid acquire sufficient momentum to break through the surface and escape into the free air. At the same time some of the molecules of water vapor in the air strike the water surface and are unable to leave it. Strictly speaking, the movement of molecules from water to air is evaporation and the reverse movement is condensation. Popularly, evaporation is considered as a net loss of mass from a liquid and condensation as a net gain to a liquid as a result of this exchange (Thornthwaite and Holzman 1942).


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  1. Albrecht, F.: Die Methoden zur Bestimmung der Verdunstung der natürlichen Erdoberfläche. Arch. Meteorol., Geophys. u. Bioklimatol., Ser. B, Allg. u. Biologische Klimatologie 2, H. 1/2, 1–38 (1950).CrossRefGoogle Scholar
  2. Anderson, D. B.: Relative humidity or vapor pressure deficit. Ecology 17, 277–282 (1936).CrossRefGoogle Scholar
  3. Bennett, M. G.: The condensation of water in the atmosphere. Roy. Met. Soc., London, Quart. J. 50, 3–14 (1934).Google Scholar
  4. Haude, W.: Verdunstungsmenge und Evaporationskraft eines Klimas. Ber. dtsch. Wetterdienstes i. d. US-Zone 42, 225–229 (1952).Google Scholar
  5. Kelvin (Baron), William Thomson: On the equilibrium of vapour at a curved surface of liquid. Roy. Soc. Edinb., Proc. (1869–72) 7, 63–68 (1872).Google Scholar
  6. Leighly, John: A Note on Evaporation. Ecology 18, 180–198 (1937).CrossRefGoogle Scholar
  7. Thornthwaite, C. W.: Atmospheric moisture in relation to ecological problems. Ecology 21, 17–28 (1940).CrossRefGoogle Scholar
  8. A re-examination of the concept and measurement of potential evapotranspiration. The measurement of potential evapotranspiration. The Johns Hopkins Univ. Lab. of Climatology, Seabrook, New Jersey, Publications in Climatology 7, 200–209 (1954).Google Scholar
  9. Thornthwaite, C. W., and Benjamin Holzman: The determination of evaporation from land and water surfaces. U.S. Monthly Weather Review 67, 4–11 (1939).CrossRefGoogle Scholar
  10. Measurement of evaporation from land and water surfaces. U.S. Dept. of Agric. Techn. Bull. No 817, 1942, 75.Google Scholar
  11. Turnage, William V., and Edith B. Shreve: Note on atmospheric aridity. Ecology 20, 107–109 (1939).CrossRefGoogle Scholar
  12. Unger, K.: Zur Abschätzung von Verdunstungsunterschieden verschiedener Pflanzenbestände am natürlichen Standort. Angew. Meteorologie 2, 1–14 (1954).Google Scholar

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© Springer-Verlag OHG. Berlin · Göttingen · Heidelberg 1956

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  • C. W. Thornthwaite

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