A circular halo, often referred to as just a halo, is formed by the refraction of sunlight through cloud suspended ice crystals as opposed to raindrops or other liquid water suspended in the air. Sometimes only arc sections are visible as opposed to a full circle. Brighter sections can occur above, below, and lateral to the center (where the sun is visible). The lateral bright areas are referred to as "sun dogs," "parhelia" (plural), or mock suns because of their bright appearance and possible confusion with the actual location of the sun. The ones above and below the sun are the upper and lower tangent arcs, respectively. A 22 degree halo has red on the inside and blue on the outside.
These pictures were taken today. So neat.
