Re: Unusual Light Pillars Over Latvia (2009 January 12)
Posted: Sun Dec 28, 2014 7:55 am
I suspect the fanning of the pillar is due to some dispersion and/or thinning of the ice crystal density with height.
The explanation for these unusual pillars was posted on OPOD ( http://www.atoptics.co.uk/opod.htm ) some time ago. See this http://www.atoptics.co.uk/fz193.htm page. They are produced by columnar hexagonal ice crystals drifting with their long axes horizontal.
More of these pillars at -http://www.atoptics.co.uk/fz179.htm
Les Cowley (http://www.atoptics.co.uk)