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28 Clouds and Precipitation

Part 3. Meteorology and Climatology

  1. George A Isaac1,
  2. John Hallett2

Published Online: 15 APR 2006

DOI: 10.1002/0470848944.hsa031

Encyclopedia of Hydrological Sciences

Encyclopedia of Hydrological Sciences

How to Cite

Isaac, G. A. and Hallett, J. 2006. Clouds and Precipitation. Encyclopedia of Hydrological Sciences. 3:28.

Author Information

  1. 1

    Meteorological Service of Canada, Cloud Physics and Severe Weather Research Division, Toronto, ON, Canada

  2. 2

    Desert Research Institute, Division of Atmospheric Sciences, Reno, NV, US

Publication History

  1. Published Online: 15 APR 2006


Clouds and the precipitation that comes from them are important elements of the hydrological cycle. Clouds provide a blanket for our Earth, both shielding it from radiation from the Sun and trapping heat escaping from the surface. They also generate precipitation through the condensation-coalescence mechanism, which involves only liquid cloud drops, or through ice initiation leading to large ice particles and eventually snow or rain. Mean annual precipitation amounts reach a maximum near the equator, near 8 mm day−1, and decrease poleward to about 1 mm day−1. A good understanding of both cloud and precipitation processes is very important for climate and weather predictions. This paper outlines some of the most important processes and provides reference material where more detailed information can be obtained.


  • clouds;
  • precipitation;
  • snow;
  • rain;
  • ice crystals;
  • latent heat;
  • size distribution;
  • clausius-clapeyron;
  • terminal fall velocity