Atmospheric pressure

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The pressure caused by the weight of the atmosphere. A standard atmosphere (atm) is defined as the pressure exerted by a 760 mm column of mercury at standard gravity and a temperature of 0 C. This definition was set such that the mean value of the atmosphere at sea level is 1 atm (760 mm Hg). Atmospheric pressure decreases with increasing altitude. It is also dependant on temperature and humidity. The variations in atmospheric pressure are used as an indicator of weather.

Synonyms and Related Terms

atm; atmosférický tlak (Ces.); atmosfære (Dan.); Luftdruck (Deut.); presión atmosférica (Esp.); pression atmosphérique (Fr.); pressione atmosferica(It.); luchtdruk (Ned.); lufttrykk (Nor.); ciśnienie atmosferyczne (Pol.);

Physical and Chemical Properties

1 atm = 760 mm Hg = 29.92 in Hg = 1013.25 millibar (torr)

Resources and Citations

  • Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
  • ASTM, Standard Terminology Relating to Conditioning, Annual Book of ASTM Standards, Section 6, Paints, Related Coatings and Aromatics, ASTM, E41, 23-24, Sep-92
  • Van Nostrand's Scientific Encyclopedia, Douglas M. Considine (ed.), Van Nostrand Reinhold, New York, 1976
  • The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998
  • Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997