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Polarization patterns of thick clouds: overcast skies have distribution of the angle of polarization similar to that of clear skies

Hegedues, Ramon; Åkesson, Susanne LU and Horvath, Gabor (2007) In Journal of the Optical Society of America A 24(8). p.2347-2356
Abstract
The distribution of polarization in the overcast sky has been practically unknown. Earlier the polarization of light from heavily overcast skies (when the Sun's disc was invisible) has been measured only sporadically in some celestial points by point-source polarimetry. What kind of patterns of the degree p and angle a of linear polarization of light could develop after transmission through a thick layer of ice or water clouds? To answer this question, we measured the p and a patterns of numerous totally overcast skies on the Arctic Ocean and in Hungary by full-sky imaging polarimetry. We present here our finding that depending on the optical thickness of the cloud layer, the pattern of a of light transmitted through the ice or water... (More)
The distribution of polarization in the overcast sky has been practically unknown. Earlier the polarization of light from heavily overcast skies (when the Sun's disc was invisible) has been measured only sporadically in some celestial points by point-source polarimetry. What kind of patterns of the degree p and angle a of linear polarization of light could develop after transmission through a thick layer of ice or water clouds? To answer this question, we measured the p and a patterns of numerous totally overcast skies on the Arctic Ocean and in Hungary by full-sky imaging polarimetry. We present here our finding that depending on the optical thickness of the cloud layer, the pattern of a of light transmitted through the ice or water clouds of totally overcast skies is qualitatively the same as the a pattern of the clear sky. Under overcast conditions the value of a is determined predominantly by scattering on cloud particles themselves. Nevertheless, the degrees of linear polarization of light from overcast skies were rather low (p <= 16 %). Our results obtained under overcast conditions complete the earlier findings that the a pattern of the clear sky also appears in partly cloudy, foggy, and smoky skies. Our results show that the celestial distribution of the direction of polarization is a very robust pattern being qualitatively always the same under all possible sky conditions. This is of great importance for the orientation of polarization-sensitive animals based on sky polarization under conditions when the Sun is not visible. (c) 2007 Optical Society of America. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of the Optical Society of America A
volume
24
issue
8
pages
2347 - 2356
publisher
Optical Society of America
external identifiers
  • wos:000248140300021
  • scopus:38849145064
ISSN
1084-7529
language
English
LU publication?
yes
id
efcff00e-0a84-407e-96a4-31356d42c0a7 (old id 691586)
alternative location
http://www.opticsinfobase.org/abstract.cfm?URI=josaa-24-8-2347
date added to LUP
2007-12-12 12:45:41
date last changed
2017-10-29 04:14:17
@article{efcff00e-0a84-407e-96a4-31356d42c0a7,
  abstract     = {The distribution of polarization in the overcast sky has been practically unknown. Earlier the polarization of light from heavily overcast skies (when the Sun's disc was invisible) has been measured only sporadically in some celestial points by point-source polarimetry. What kind of patterns of the degree p and angle a of linear polarization of light could develop after transmission through a thick layer of ice or water clouds? To answer this question, we measured the p and a patterns of numerous totally overcast skies on the Arctic Ocean and in Hungary by full-sky imaging polarimetry. We present here our finding that depending on the optical thickness of the cloud layer, the pattern of a of light transmitted through the ice or water clouds of totally overcast skies is qualitatively the same as the a pattern of the clear sky. Under overcast conditions the value of a is determined predominantly by scattering on cloud particles themselves. Nevertheless, the degrees of linear polarization of light from overcast skies were rather low (p &lt;= 16 %). Our results obtained under overcast conditions complete the earlier findings that the a pattern of the clear sky also appears in partly cloudy, foggy, and smoky skies. Our results show that the celestial distribution of the direction of polarization is a very robust pattern being qualitatively always the same under all possible sky conditions. This is of great importance for the orientation of polarization-sensitive animals based on sky polarization under conditions when the Sun is not visible. (c) 2007 Optical Society of America.},
  author       = {Hegedues, Ramon and Åkesson, Susanne and Horvath, Gabor},
  issn         = {1084-7529},
  language     = {eng},
  number       = {8},
  pages        = {2347--2356},
  publisher    = {Optical Society of America},
  series       = {Journal of the Optical Society of America A},
  title        = {Polarization patterns of thick clouds: overcast skies have distribution of the angle of polarization similar to that of clear skies},
  volume       = {24},
  year         = {2007},
}