air mass

air mass
   a unit used in astronomy in measuring the absorption of light from the stars by the atmosphere. One air mass is the amount of absorption of light from a star directly overhead (at the zenith). The absorption of light from other stars is greater, because their light must pass obliquely through the atmosphere. If Z is the zenithal angle, the angle between the star and the zenith, then the absorption of its light is estimated to be sec Z air masses, "sec" being the secant trigonometric function.

Dictionary of units of measurement. 2015.

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  • air mass — air′ mass n. mer a body of air covering a wide area, exhibiting approximately uniform properties through any horizontal section • Etymology: 1890–95 …   From formal English to slang

  • air mass — n. Meteorol. a huge, uniform body of air having the properties of its place of origin: see POLAR CONTINENTAL, POLAR MARITIME, TROPICAL CONTINENTAL, TROPICAL MARITIME …   English World dictionary

  • Air mass — For other uses, see Air mass (astronomy) and Air mass (solar energy). Different air masses which affect North America, as well as othe …   Wikipedia

  • air mass — a body of air covering a relatively wide area, exhibiting approximately uniform properties through any horizontal section. [1890 95] * * * In meteorology, a large body of air having nearly uniform conditions of temperature and humidity at any… …   Universalium

  • air mass — noun a large body of air with uniform characteristics horizontally • Hypernyms: ↑atmosphere, ↑atmospheric state • Hyponyms: ↑high, ↑low, ↑depression * * * noun : a body of air extending hundreds or thousands of miles horizontally and someti …   Useful english dictionary

  • air mass — /ˈɛə mæs / (say air mas) noun a large body of air, up to thousands of kilometres in extent, of uniform temperature and humidity, and impacting on an adjacent air mass at a well defined front; classified according to temperature as Arctic,… …  

  • Air-mass thunderstorm — An Air mass thunderstorm, also called a garden variety thunderstorm, is a thunderstorm that is generally weak and usually not severe. These storms form in environments with low Convective Available Potential Energy (CAPE) values, low wind shear,… …   Wikipedia

  • Air mass coefficient — The air mass coefficient characterizes the solar spectrum after the solar radiation has traveled through the atmosphere. For a thickness l o of the atmosphere, the path length l through the atmosphere for solar radiation incident at angle θ… …   Wikipedia

  • air mass classification — noun a) Meteorology. a system used to identify and to characterize the different air masses according to a basic scheme. A number of systems have been proposed, but the Bergeron classification has been the most widely accepted. In this system,… …   Wiktionary

  • air mass weather — noun : weather within an air mass in distinction from that occurring at its front …   Useful english dictionary

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