November - fog You are here: Home Photo gallery Atmospheric optics Ice crystal halos 46o halo


A halo around the sun or moon with a radius of 46 degrees, caused by refraction of light by randomly oriented hexagonal ice crystals. This halo is rare, in extremely rare cases it may actually be seen as a complete circle. As the light path cross-section through a hexagonal ice crystal for the 46-degrees halo is very small compared to the common 22-degrees halo, the refactive angle is much more determined and fixed, and as a result the 46 degrees halo shows a much clearer color spectrum.

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