When the Sun is low, sundogs (also called parhelia or mock suns) can appear on the 22-degree solar halo (which is too faint to be seen here) on a line through the Sun parallel to the horizon. They are caused by refraction through hexagonal ice crystals in light clouds aligned perpendicular to the horizon, and are colored red on the inside (toward the Sun), blue on the outside. They are also commonly seen in blowing snow.