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Applied Optics

Applied Optics

APPLICATIONS-CENTERED RESEARCH IN OPTICS

  • Editor: James C. Wyant
  • Vol. 47, Iss. 34 — Dec. 1, 2008
  • pp: H116–H127

Observed brightness distributions in overcast skies

Raymond L. Lee, Jr. and David E. Devan  »View Author Affiliations


Applied Optics, Vol. 47, Issue 34, pp. H116-H127 (2008)
http://dx.doi.org/10.1364/AO.47.00H116


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Abstract

Beneath most overcasts, clouds’ motions and rapidly changing optical depths complicate mapping their angular distributions of luminance L v and visible-wavelength radiance L. Fisheye images of overcast skies taken with a radiometer-calibrated digital camera provide a useful new approach to solving this problem. Maps calculated from time-averaged images of individual overcasts not only show their brightness distributions in unprecedented detail, but they also help solve a long-standing puzzle about where brightness maxima of overcasts are actually located. When combined with simulated radiance distributions from MODTRAN4, our measured radiances also let us estimate the gradients of cloud thickness observed in some overcasts.

© 2008 Optical Society of America

OCIS Codes
(010.1290) Atmospheric and oceanic optics : Atmospheric optics
(120.5630) Instrumentation, measurement, and metrology : Radiometry
(290.1090) Scattering : Aerosol and cloud effects
(010.1615) Atmospheric and oceanic optics : Clouds
(010.7295) Atmospheric and oceanic optics : Visibility and imaging
(010.5630) Atmospheric and oceanic optics : Radiometry

History
Original Manuscript: April 21, 2008
Manuscript Accepted: June 6, 2008
Published: September 12, 2008

Citation
Raymond L. Lee, Jr., and David E. Devan, "Observed brightness distributions in overcast skies," Appl. Opt. 47, H116-H127 (2008)
http://www.opticsinfobase.org/ao/abstract.cfm?URI=ao-47-34-H116


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