Thursday, 8 October 2009
Asymmetric intensity of 22° halo on ice surface
This 22° halo on ice surface was seen on 17 January in Tampere. It was more pronounced on the right side. Intensity asymmetry was not caused by local changes in crystal densities because it was seen wherever I walked on the ice.
The effect must be made by atsimuthally oriented crystals on the lake ice. Possibly wind blowing from one direction had caused non-uniform deposition of moisture, resulting in (poorly) atsimuthally locked crystals.
See animation ( 1 ), which involves about 70 photos taken during 30 meters camera movement. The asymmetry effect is also seen in stacked image of 117 frames ( 2 )
This is not the first time when asymmetry of halos on ice surface has been noticed. In December 2007 Jari Piikki photographed curiously inclined halos in Juva ( 3 ).