Upper Lowitz arc - San Francisco


Upper Lowitz arc, San Francisco imaged on 17th November 2006 by Mila Zinkova.
©Mila Zinkova, shown with permission.

The arc is apparent as the bright 10 o'clock 22° halo region and possibly above.
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Arcs like this could be produced by column crystals rocking about a Lowitz axis perpendicular to the long 'c' axis as suggested by Riikonen et.al.