Difference between revisions of "Precipitation attenuation"

From Glossary of Meteorology
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<div class="definition"><div class="short_definition">[[Attenuation]] of [[electromagnetic waves]] propagating through [[precipitation]].  Depending on the [[wavelength]] of the [[radiation]], the attenuation is accounted for by some  combination of [[absorption]] and [[scattering]] by the precipitation particles.</div><br/> <div class="paragraph">The relative importance of scattering tends to increase as the wavelength becomes shorter. For  [[radar]], the [[specific attenuation]] ''Y'' (dB km<sup>-1</sup>) due to [[rain]] is described by empirical power relations  of the form ''Y'' = ''aR''<sup>''b''</sup>, where ''R'' (mm h<sup>-1</sup>) is the [[rainfall rate]], and ''a'' and ''b'' are empirical constants  that depend on wavelength and [[temperature]]. The specific attenuation of [[snow]] is less than that  of rain, and for wavelengths of 10 cm and longer is usually negligible. For [[lidar]], the precipitation  attenuation is approximately proportional to the cross-sectional area of the precipitation particles  per unit volume. <br/>''See'' [[rain attenuation]]; <br/>''compare'' [[cloud attenuation]].</div><br/> </div>
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<div class="definition"><div class="short_definition">[[attenuation|Attenuation]] of [[electromagnetic waves]] propagating through [[precipitation]].  Depending on the [[wavelength]] of the [[radiation]], the attenuation is accounted for by some  combination of [[absorption]] and [[scattering]] by the precipitation particles.</div><br/> <div class="paragraph">The relative importance of scattering tends to increase as the wavelength becomes shorter. For  [[radar]], the [[specific attenuation]] ''Y'' (dB km<sup>-1</sup>) due to [[rain]] is described by empirical power relations  of the form ''Y'' = ''aR''<sup>''b''</sup>, where ''R'' (mm h<sup>-1</sup>) is the [[rainfall rate]], and ''a'' and ''b'' are empirical constants  that depend on wavelength and [[temperature]]. The specific attenuation of [[snow]] is less than that  of rain, and for wavelengths of 10 cm and longer is usually negligible. For [[lidar]], the precipitation  attenuation is approximately proportional to the cross-sectional area of the precipitation particles  per unit volume. <br/>''See'' [[rain attenuation]]; <br/>''compare'' [[cloud attenuation]].</div><br/> </div>
 
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Latest revision as of 17:39, 25 April 2012



precipitation attenuation

Attenuation of electromagnetic waves propagating through precipitation. Depending on the wavelength of the radiation, the attenuation is accounted for by some combination of absorption and scattering by the precipitation particles.

The relative importance of scattering tends to increase as the wavelength becomes shorter. For radar, the specific attenuation Y (dB km-1) due to rain is described by empirical power relations of the form Y = aRb, where R (mm h-1) is the rainfall rate, and a and b are empirical constants that depend on wavelength and temperature. The specific attenuation of snow is less than that of rain, and for wavelengths of 10 cm and longer is usually negligible. For lidar, the precipitation attenuation is approximately proportional to the cross-sectional area of the precipitation particles per unit volume.
See rain attenuation;
compare cloud attenuation.