Extinction Coefficient

This definition page has been automatically generated. You can help ExoDictionary by expanding, updating, or correcting it.

This autostub has not yet had its initial copyediting proof and may contain significant formatting and even factual errors. You can improve Exodictionary by cleaning up the page markup and verifying that the definition is correct and then removing this tag.

This autostub has not yet had its initial categorization proof and may be categorized incorrectly. You can improve Exodictionary by removing inappropriate categories and then removing this tag.

Extinction Coefficient

</dt>
In meteorology, a measure of the space rate of diminution, or extinction, of any transmitted light; thus, it is the attenuation coefficient applied to visible radiation. The extinction coefficient Missing Image:img src="SP7-e_files/epsilonsm.gif" is identified as

dI = -Missing Image:img src="SP7-e_files/epsilonsm.gif"I dx or I = I₀ e^{-Missing Image:img src="SP7-e_files/epsilonsm.gif"x} where I is the

illuminance (luminous flux density) at the selected point in space, I₀ is the illuminance at the light source; and x is the distance from the source. </dd>
When so used, the extinction coefficient equals the sum of the medium's absorption coefficient and scattering coefficient, each computed as a weighted average over all wavelengths in the visible spectrum. As long as scattering effects are primary, as in the lower atmosphere, the value of the extinction coefficient is a function of the particle size of atmospheric suspensoids. It varies in order of magnitude from 10 per kilometer with very low visibility to 0.01 per kilometer in very clear air. </dd>

References

This article is based on NASA's Dictionary of Technical Terms for Aerospace Use