Sundogs Over Lofer, Austria
March 23, 2009
The photo above showing a dazzling pair of sundogs and a parhelic circle was captured in Lofer, Austria, early on the afternoon of January 3, 2009. On this very cold winter's day, despite the clear skies, small ice crystals, sometimes called diamond dust, were falling through the air. Blowing snow was also quite evident. Sundogs or parhelia form when sunlight is refracted through side faces of oriented hexagonal plate crystals, exiting through their alternate side faces. Several reflections may occur during the transit. In order to observe the parhelic circle, sunlight must be reflected from the front surfaces of any crystal face in the vertical plane.