Light pillar
A light pillar is a visual phenomenon created by the reflection of light from ice crystals with near horizontal parallel planar surfaces. The light can come from the Sun (usually at or low to the horizon) in which case the phenomenon is called a sun pillar or solar pillar. It can also come from the Moon or from terrestrial sources such as streetlights.[1]
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Light pillars are a kind of optical phenomenon which is formed by the reflection of sunlight or moonlight by ice crystals that are present in the Earth's atmosphere.
The light pillar looks like a thin column that extends vertically above and/or below the source of light. The light pillar is prominently visible when the Sun is low or lies below the horizon. It normally forms an arc that extends from five to ten degrees beyond the solar disc. Light pillars can sometimes also be seen arising from the Moon.
Light pillars are formed by reflection from ice crystals with roughly horizontal faces.
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Pillars from uncovered work lights above University of Alaska Fairbanks (J. Hall)
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Sunset with prominent sun pillar near Tucson, Arizona.
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Sun pillar in San Francisco, California.
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Sun pillar over Lake Lucerne, Wisconsin.
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A light pillar formed at sunset near Toronto, Ontario.
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[edit] References
- ^ "Nature's spotlights". San Francisco Chronicle. 2009-01-29. http://www.sfgate.com/cgi-bin/object/dayinpictures?f=/g/a/2009/01/28/dip.DTL&o=12&type=dayinpictures.
[edit] External links
- Pillars. Atmospheric Optics. Explanations (10 pages) and many images.
- Light Pillars: An Introduction to Sun Pillars and Related Phenomena. The Weather Doctor's Weather Eyes. Another nice explanation, all on one page
- Fabulous frozen frames - Sydney Morning Herald. November 1, 2006
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Wikimedia Commons has media related to: Sun pillar |
- A Sun Pillar Over North Carolina. NASA Astronomy Picture of the Day, 15 December 2008
- Interactive view of sky-wide artificial light pillar show photographed in Finland, November 2010.
