
22˚ Halo with Moon Dogs (by Bob West)
A 22° halo is an optical phenomenon which produces a halo of 22° around the sun or moon. This occurs when light is being refracted through hexagonal ice crystals that float high in the atmosphere when a haze of cirrus or cirrostratus clouds are present.
The two brighter spots on either side of the Moon are called Moon Dogs, which are a rarer event caused also by the refraction of moonlight that passes through hexagonal plate shaped ice crystals that tend to fall at a different orientation (flat) in the same clouds as the halo when the moonlight is strong enough.