Elliptical Halo imaged by Claudia Hinz (atmospheric optics) from Mount Wendelstein, Germany on
13th March '06. Images ©Claudia Hinz, shown with permission.
The display started at a temperature of -17 C. Diamond dust had formed from dissipating stratus in the valley. The first halos were a bright lower sun pillar/subsun. A rare elliptical halo then became visible. Like the that in the previous OpticsPOD, Claudia's elliptical had at least two rings. The outer was of 8° long axis and 3° short with an inner ring 2° tall and ~0.5° wide. Elliptical halos are small and easily missed unless looked for carefully with the sun well shielded. They appear to have no fixed size and if indeed they are formed from improbably obtuse pyramidal crystals their size must change with solar altitude. However, the pyramidal crystal interpretation is suspect because ray tracing simulations have so far not matched the ring characteristics precisely.