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  Lowitz crystal sun pillars 













Crystals with Lowitz orientations, i.e. ones taking all orientations about the nearly horizontalred rotation axis shown below, form sun pillars in addition to the rare Lowitz arcs.

The pillars arise for the very same reasons as those produced by column crystals. The combination of the two possible crystal rotations causes the prism end faces to have a greater probability of being nearly horizontal than being inclined at other angles.

Sunlight reflected off the end faces when they are nearly horizontal faces produces the pillars.


 
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A sun pillar, sundogs and what at first sight looks like a 22° halo all produced by plate crystals with rare Lowitz orientations. The pillar and sundogs appear because the prism end faces of Lowitz oriented crystals are more likely to be nearly horizontal than be otherwise tilted. Lowitz pillars are tall even when the sun is moderately high. The almost circular halo is a combination of the upper and lower circular Lowitz arcs. HaloSim simulation. for a solar elevation of 1º.