Could Vikings have navigated under foggy and cloudy conditions by skylight polarization? On the atmospheric optical prerequisites of polarimetric Viking navigation under foggy and cloudy skies
In sunshine, the Vikings navigated on the open sea using sundials. According to a widespread hypothesis, when the Sun was occluded by fog or clouds the Vikings might have navigated by skylight polarization detected with an enigmatic birefringent crystal(sunstone). There are two atmospheric optical p...
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ftunivzuerich:oai:www.zora.uzh.ch:283 2024-09-09T19:23:35+00:00 Could Vikings have navigated under foggy and cloudy conditions by skylight polarization? On the atmospheric optical prerequisites of polarimetric Viking navigation under foggy and cloudy skies Hegedüs, R Akesson, S Wehner, R Horváth, G 2007-02 https://www.zora.uzh.ch/id/eprint/283/ https://www.zora.uzh.ch/283 https://doi.org/10.1098/rspa.2007.1811 eng eng The Royal Society https://www.zora.uzh.ch/283 doi:10.1098/rspa.2007.1811 urn:issn:1364-5021 info:eu-repo/semantics/closedAccess Hegedüs, R; Akesson, S; Wehner, R; Horváth, G (2007). Could Vikings have navigated under foggy and cloudy conditions by skylight polarization? On the atmospheric optical prerequisites of polarimetric Viking navigation under foggy and cloudy skies. Proceedings of the Royal Society of London, Series A, 463(2080):1081-1095. Institute of Zoology (former) 570 Life sciences biology 590 Animals (Zoology) Journal Article PeerReviewed info:eu-repo/semantics/article 2007 ftunivzuerich https://doi.org/10.1098/rspa.2007.1811 2024-08-06T23:54:52Z In sunshine, the Vikings navigated on the open sea using sundials. According to a widespread hypothesis, when the Sun was occluded by fog or clouds the Vikings might have navigated by skylight polarization detected with an enigmatic birefringent crystal(sunstone). There are two atmospheric optical prerequisites for this alleged polarimetric Viking navigation under foggy/cloudy skies: (1) the degree of linear polarization p of skylight should be high enough and (2) at a given Sun position, the pattern of the angle of polarization a of the foggy/cloudy sky should be similar to that of the clear sky. Until now, these prerequisites have not been investigated. Using full-sky imaging polarimetry, we measured the p- and a-patterns of Arctic foggy and cloudy skies when the Sun was invisible. These patterns were compared with the polarization patterns of clear Arctic skies. We show here that although prerequisite (2) is always fulfilled under both foggy and cloudy conditions, if the fog layer is illuminated by direct sunlight, prerequisite (1) is usually satisfied only for cloudy skies. In sunlit fog, the Vikings could have navigated by polarization only, if p of light from the foggy sky was sufficiently high. Article in Journal/Newspaper Arctic University of Zurich (UZH): ZORA (Zurich Open Repository and Archive Arctic Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 463 2080 1081 1095 |
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Open Polar |
collection |
University of Zurich (UZH): ZORA (Zurich Open Repository and Archive |
op_collection_id |
ftunivzuerich |
language |
English |
topic |
Institute of Zoology (former) 570 Life sciences biology 590 Animals (Zoology) |
spellingShingle |
Institute of Zoology (former) 570 Life sciences biology 590 Animals (Zoology) Hegedüs, R Akesson, S Wehner, R Horváth, G Could Vikings have navigated under foggy and cloudy conditions by skylight polarization? On the atmospheric optical prerequisites of polarimetric Viking navigation under foggy and cloudy skies |
topic_facet |
Institute of Zoology (former) 570 Life sciences biology 590 Animals (Zoology) |
description |
In sunshine, the Vikings navigated on the open sea using sundials. According to a widespread hypothesis, when the Sun was occluded by fog or clouds the Vikings might have navigated by skylight polarization detected with an enigmatic birefringent crystal(sunstone). There are two atmospheric optical prerequisites for this alleged polarimetric Viking navigation under foggy/cloudy skies: (1) the degree of linear polarization p of skylight should be high enough and (2) at a given Sun position, the pattern of the angle of polarization a of the foggy/cloudy sky should be similar to that of the clear sky. Until now, these prerequisites have not been investigated. Using full-sky imaging polarimetry, we measured the p- and a-patterns of Arctic foggy and cloudy skies when the Sun was invisible. These patterns were compared with the polarization patterns of clear Arctic skies. We show here that although prerequisite (2) is always fulfilled under both foggy and cloudy conditions, if the fog layer is illuminated by direct sunlight, prerequisite (1) is usually satisfied only for cloudy skies. In sunlit fog, the Vikings could have navigated by polarization only, if p of light from the foggy sky was sufficiently high. |
format |
Article in Journal/Newspaper |
author |
Hegedüs, R Akesson, S Wehner, R Horváth, G |
author_facet |
Hegedüs, R Akesson, S Wehner, R Horváth, G |
author_sort |
Hegedüs, R |
title |
Could Vikings have navigated under foggy and cloudy conditions by skylight polarization? On the atmospheric optical prerequisites of polarimetric Viking navigation under foggy and cloudy skies |
title_short |
Could Vikings have navigated under foggy and cloudy conditions by skylight polarization? On the atmospheric optical prerequisites of polarimetric Viking navigation under foggy and cloudy skies |
title_full |
Could Vikings have navigated under foggy and cloudy conditions by skylight polarization? On the atmospheric optical prerequisites of polarimetric Viking navigation under foggy and cloudy skies |
title_fullStr |
Could Vikings have navigated under foggy and cloudy conditions by skylight polarization? On the atmospheric optical prerequisites of polarimetric Viking navigation under foggy and cloudy skies |
title_full_unstemmed |
Could Vikings have navigated under foggy and cloudy conditions by skylight polarization? On the atmospheric optical prerequisites of polarimetric Viking navigation under foggy and cloudy skies |
title_sort |
could vikings have navigated under foggy and cloudy conditions by skylight polarization? on the atmospheric optical prerequisites of polarimetric viking navigation under foggy and cloudy skies |
publisher |
The Royal Society |
publishDate |
2007 |
url |
https://www.zora.uzh.ch/id/eprint/283/ https://www.zora.uzh.ch/283 https://doi.org/10.1098/rspa.2007.1811 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic |
genre_facet |
Arctic |
op_source |
Hegedüs, R; Akesson, S; Wehner, R; Horváth, G (2007). Could Vikings have navigated under foggy and cloudy conditions by skylight polarization? On the atmospheric optical prerequisites of polarimetric Viking navigation under foggy and cloudy skies. Proceedings of the Royal Society of London, Series A, 463(2080):1081-1095. |
op_relation |
https://www.zora.uzh.ch/283 doi:10.1098/rspa.2007.1811 urn:issn:1364-5021 |
op_rights |
info:eu-repo/semantics/closedAccess |
op_doi |
https://doi.org/10.1098/rspa.2007.1811 |
container_title |
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences |
container_volume |
463 |
container_issue |
2080 |
container_start_page |
1081 |
op_container_end_page |
1095 |
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1809893586429280256 |