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Odd Radius Halos seen by Russell Sampson at Eastern Connecticut State University, Willimantic, CT on April 10, '08. The sun is hidden behind the library building. ©Russell Sampson, shown with permission.

Six sided pyramidal ice crystals make the halos. Rays passing through them enter and leave through faces with a number of different inclinations to each other resulting in circular halos of many different radii.

This rare display has an unusually complete set including the rare outer 35° halo - “The 35 was persistent and visual (i.e. I could see it and it stayed in the same place over many minutes) so I’m confident it is not spurious.

The lower sector is contrast enhanced and unsharp masked.

Odd radius halos
Pyramidal crystals