Optical air mass: Difference between revisions

Latest revision as of 14:47, 20 February 2012

optical air mass[edit | edit source]

(Originally called air mass.) A measure of the length of the path through the atmosphere to sea level traversed by light rays from a celestial body, expressed as a multiple of the pathlength for a light source at the zenith.

It is approximately equal to the secant of the zenith distance of the given celestial body for zenith distances up to about 70°. Bemporad's formula must be used for more accurate determination. To get a representative value at high elevation, the above values must be multiplied by the ratio of the actual atmospheric pressure to the sea level pressure.

List, R. J., Ed. 1951. Smithsonian Meteorological Tables. 6th rev. ed., . p. 422.

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-<div class="definition"><div class="short_definition">(Originally called air mass.) A measure of the length of the path through the  [[atmosphere]] to [[sea level]] traversed by [[light]] rays from a celestial body, expressed as a multiple of  the pathlength for a light source at the [[zenith]].</div><br/> <div class="paragraph">It is approximately equal to the secant of the [[zenith distance]] of the given celestial body for  zenith distances up to about 70&deg;. [[Bemporad's formula]] must be used for more accurate determination.  To get a representative value at high elevation, the above values must be multiplied by  the ratio of the actual [[atmospheric pressure]] to the [[sea level pressure]].</div><br/> </div><div class="reference">List, R. J., Ed. 1951. Smithsonian Meteorological Tables. 6th rev. ed., . p. 422. </div><br/>
+<div class="definition"><div class="short_definition">(Originally called air mass.) A measure of the length of the path through the  [[atmosphere]] to [[sea level]] traversed by [[light]] rays from a celestial body, expressed as a multiple of  the pathlength for a light source at the [[zenith]].</div><br/> <div class="paragraph">It is approximately equal to the secant of the [[zenith distance]] of the given celestial body for  zenith distances up to about 70&#x000b0;. [[Bemporad's formula]] must be used for more accurate determination.  To get a representative value at high elevation, the above values must be multiplied by  the ratio of the actual [[atmospheric pressure]] to the [[sea level pressure]].</div><br/> </div><div class="reference">List, R. J., Ed. 1951. Smithsonian Meteorological Tables. 6th rev. ed., . p. 422. </div><br/>
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