Parhelia (sundogs or mock suns) are bright colorful spots in cirrus
clouds. They are found at the same altitude as the sun and never less
than 22 degrees from it. They are usually a few degrees across and may
be extended either vertically or horizontally. Parhelia usually come
in pairs, one on each side of the sun, and are quite common.
They are reddish on the side facing the sun and often have bluish-white
tails stretching horizontally away from them. Parhelia are formed by
refraction of light between 60 degree prism faces in horizontally oriented