Halo

Rings or arcs that encircle the sun or moon when seen through an ice crystal cloud or a sky filled with falling ice crystals. Halos are produced by reflection of light by ice crystals suspended in the earth's atmosphere and exhibiting prismatic coloration ranging from red inside to blue outside.

Halo Group of optical phenomena, in the form of rings, arcs, pillars or bright spots around the Sun or Moon, produced by the refraction or reflection of light by ice crystals suspended in the atmosphere (Cirrus clouds, diamond dust, etc.)

Any of a variety of bright circles or arcs centered on the sun or moon, caused by the refraction or reflection of light by ice crystals suspended in the earth's atmosphere and exhibiting prismatic coloration ranging from red inside to blue outside.