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. Mouse over for an enhanced view. 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.