Optical attenuation in fog and clouds

Robert Michael Pierce; Jaya Ramaprasad; Eric C. Eisenberg

doi:10.1117/12.449815

27 November 2001 Optical attenuation in fog and clouds

Robert Michael Pierce, Jaya Ramaprasad, Eric C. Eisenberg

Proceedings Volume 4530, Optical Wireless Communications IV; (2001) https://doi.org/10.1117/12.449815
Event: ITCom 2001: International Symposium on the Convergence of IT and Communications, 2001, Denver, CO, United States

Abstract

The Kruse formula was originally devised to relate visibility to optical attenuation, from the visible to the near infrared (IR), for dust and small particle aerosols with dimensions much smaller than the wavelength. Application of this formula to attenuation in fog is not appropriate since fogs consist mainly of particles much larger than optical wavelengths. Mie scattering calculations, transmission measurements and simple observations indicate that attenuation from the visible to the near IR is virtually independent of wavelength. The Kruse formula is also shown to be questionable apart form its wavelength dependence; it does not account for scattering into the field of view and does not consider background illumination. In the derivation presented here the visibility is linked to near-forward scattering, not explicitly to attenuation. We conclude that attenuation in fog should be treated as virtually wavelength independent from the visible to the near IR and a more appropriate formula is (Gamma) (V;(lambda) )=(kappa) divided byV(dB/km) where V is the visual range and 8.5dB,(kappa) <17dB.

Citation Download Citation

Robert Michael Pierce, Jaya Ramaprasad, and Eric C. Eisenberg "Optical attenuation in fog and clouds", Proc. SPIE 4530, Optical Wireless Communications IV, (27 November 2001); https://doi.org/10.1117/12.449815

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