The 22° winter halo
A 22° halo is a halo, one type of optical phenomenon, forming a circle 22° around the sun, or occasionally the moon (also called a moon ring or winter halo). It forms as sunlight is refracted in millions of randomly oriented hexagonal ice crystals suspended in the atmosphere. The halo is large; the radius is roughly the size of an outstretched hand at arms length. A 22° halo may be visible on as many as 100 days per year.