Difference between revisions of "Extinction coefficient"

From Glossary of Meteorology
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<div class="definition"><div class="short_definition">(<br/>''Also called'' [[attenuation coefficient]], especially in reference to [[radar]] frequencies.)  For [[radiation]] propagating through a medium, the fractional depletion of [[radiance]] per  unit path length.</div><br/> <div class="paragraph">The [[volume extinction coefficient]] is defined through [[Beer's law]] as  <div class="display-formula"><blockquote>[[File:ams2001glos-Ee68.gif|link=|center|ams2001glos-Ee68]]</blockquote></div> where ''L'' is the [[monochromatic]] radiance at a given [[wavelength]], &gamma; is the volume extinction  coefficient, and ''ds'' is an increment of path length. The mass extinction coefficient equals the volume  extinction coefficient divided by the [[density]] of the medium. Thus, in [[SI]] units, the volume extinction  coefficient has units of inverse meters and the mass extinction coefficient has units of square meters  per kilogram. In general, [[extinction]] of [[radiant energy]] is caused by [[absorption]] and [[scattering]].  The extinction coefficient is the sum of the [[absorption coefficient]] and the [[scattering coefficient]],  and generally depends on wavelength and [[temperature]]. <br/>''Compare'' [[specific attenuation]].</div><br/> </div>
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<div class="definition"><div class="short_definition">(''Also called'' [[attenuation coefficient]], especially in reference to [[radar]] frequencies.)  For [[radiation]] propagating through a medium, the fractional depletion of [[radiance]] per  unit path length.</div><br/> <div class="paragraph">The [[volume extinction coefficient]] is defined through [[Beer's law]] as  <div class="display-formula"><blockquote>[[File:ams2001glos-Ee68.gif|link=|center|ams2001glos-Ee68]]</blockquote></div> where ''L'' is the [[monochromatic]] radiance at a given [[wavelength]], &gamma; is the volume extinction  coefficient, and ''ds'' is an increment of path length. The mass extinction coefficient equals the volume  extinction coefficient divided by the [[density]] of the medium. Thus, in [[SI]] units, the volume extinction  coefficient has units of inverse meters and the mass extinction coefficient has units of square meters  per kilogram. In general, [[extinction]] of [[radiant energy]] is caused by [[absorption]] and [[scattering]].  The extinction coefficient is the sum of the [[absorption coefficient]] and the [[scattering coefficient]],  and generally depends on wavelength and [[temperature]]. <br/>''Compare'' [[specific attenuation]].</div><br/> </div>
 
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Latest revision as of 15:12, 20 February 2012



extinction coefficient

(Also called attenuation coefficient, especially in reference to radar frequencies.) For radiation propagating through a medium, the fractional depletion of radiance per unit path length.

The volume extinction coefficient is defined through Beer's law as
ams2001glos-Ee68
where L is the monochromatic radiance at a given wavelength, γ is the volume extinction coefficient, and ds is an increment of path length. The mass extinction coefficient equals the volume extinction coefficient divided by the density of the medium. Thus, in SI units, the volume extinction coefficient has units of inverse meters and the mass extinction coefficient has units of square meters per kilogram. In general, extinction of radiant energy is caused by absorption and scattering. The extinction coefficient is the sum of the absorption coefficient and the scattering coefficient, and generally depends on wavelength and temperature.
Compare specific attenuation.