Sun dogs (or sundogs), mock suns or phantom suns, meteorological name parhelia (singular parhelion), are an atmospheric phenomenon that consists of a pair of bright spots on either horizontal side on the Sun, often co-occurring with a luminous ring known as a 22° halo. Sun dogs are a member of a large family of halos, created by light interacting with ice crystals in the atmosphere. Sun dogs typically appear as two subtly colored patches of light to the left and right of the Sun, approximately 22° distant and at the same elevation above the horizon as the Sun. They can be seen anywhere in the world during any season, but they are not always obvious or bright. Sun dogs are best seen and are most conspicuous when the Sun is close to the horizon. Sun dogs are commonly caused by the refraction of light from plate-shaped hexagonal ice crystals either in high and cold cirrus or cirrostratus clouds or, during very cold weather, drifting in the air at low levels, in which case they are called diamond dust. The crystals act as prisms, bending the light rays passing through them with a minimum deflection of 22°. As the crystals gently float downwards with their large hexagonal faces almost horizontal, sunlight is refracted horizontally, and sun dogs are seen to the left and right of the Sun. Larger plates wobble more, and thus produce taller sundogs.