So what, exactly, causes this phenomenon?

http://www.islandnet.com/~see/weather/eyes/pillars.htm
http://www.sundog.clara.co.uk/halo/lpil.htm

Plate ice crystals, which are also responsible for sundogs.

Here's a wicked 'sundog' with ALL the possible reflection
and refraction patterns possible. A real photo taken at
the southpole.

http://www.polar.org/antsun/oldissue...Polesundog.jpg




Dean A. Scott, mfa
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School of Visual Art and Design
southern adventist university
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http://www.southern.edu/~dascott