Ice Corona? ~ Pictured by Claudia Hinz (atmospheric optics) from high on Mount Wendelstein, Germany. A classic corona decorated with nearby ice crystal glints.  ©Claudia Hinz, shown with permission.

There is a bright central aureole fringed with straw colours and red. Surrounding it are concentric coloured rings, blue/green on the inner edge and purple outside. There are traces of three rings.

A corona is a diffraction pattern. Micron sized objects (water droplets or ice crystals) scatter sunlight - primarily from their outer edge.

The scattered waves overlap and interfere. In some outward directions the wave crests coincide to give a bright ring there is brightness. In some directions the wave crests are out of phase and destructive interference results in darkness. The angles of bright and dark are wavelength dependent and thus the corona has rings of complex overlapping colours.

Claudia's image has ice crystals drifting nearby in the cold mountain air. The corona could have been made by smaller ice crystals and supercooled water droplets are a second possibility.


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