September - rain You are here: Home Photo gallery Atmospheric optics Ice crystal halos 22o halo


A halo around the sun or moon with a radius of 22 degrees, caused by refraction of light by randomly oriented hexagonal ice crystals. This halo is very common; pieces of it may be seen on 200 days per year. Often, it is very faint, but in some cases it will be brilliant and complete. The inner edge of the halo is reddish colored, while the other colors of the spectrum are overlapping on the outer side of the halo, making it yellow to whitish rather than pure spectrally colored.

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