Light pillar
A light pillar or ice pillar is an
Formation
Since they are caused by the interaction of light with
ice crystals, light pillars belong to the family of halos. The crystals responsible for light pillars usually consist of flat, hexagonal plates, which tend to orient themselves more or less horizontally as they fall through the air. Each flake acts as a tiny mirror which reflects light sources that are appropriately positioned below it (see drawing), and the presence of flakes at a spread of altitudes causes the reflection to be elongated vertically into a column. The larger and more numerous the crystals, the more pronounced this effect becomes. More rarely, column-shaped crystals can cause light pillars as well.[3] In very cold weather, the ice crystals can be suspended near the ground, in which case they are referred to as diamond dust.[4]
Unlike a
vertical plane, direct the light rays towards the observer (See drawing). This is similar to viewing a light source on a body of water. Ripples on the surface of the water reflect the light source in many directions, and those that happen to be aimed at the viewer, combine to form a bright line pointing toward the light source.[5]
Images
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Light pillars caused by artificial lights, overNorth Bay Ontario, Canada -
Pillars from uncovered work lights above University of Alaska Fairbanks -
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Sun pillar in San Francisco, California. -
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Light pillars during a winter night in Stockholm, Sweden. -
A lower sun pillar seen in the Antarctic. -
A sun pillar seen in Ohio in January 2015. -
Light pillars in Rochester, New York. -
Light pillar just after sunset from the Netherlands. -
Light pillar in the Wasatch Mountains of Utah -
Light Pillars inRaubichi, Belarus on a cold night in January. -
Light pillar in Lipetsk, Russia. -
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Light pillar produced by lava from Mauna Loa in Hawaii during its 2022 eruption
See also
References
- ^ "Colonne lumineuse". World Meteorological Organization. Archived from the original on 23 September 2016.
- ^ "Light Pillar over Volcanic Etna". science.nasa.gov. NASA. 15 November 2021. Retrieved 6 December 2022.
- ^ "Sun pillars from column crystals". www.atoptics.co.uk.
- ^ "APOD: 2013 December 18 – Light Pillars over Finland". apod.nasa.gov.
- ^ "Light Pillars". www.atoptics.co.uk.
External links
Wikimedia Commons has media related to Sun pillar.
- 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
- A Sun Pillar Over North Carolina. NASA Astronomy Picture of the Day, 15 December 2008