An optical phenomenon resulting from the refraction and reflection of sunlight within ice crystals in cirrus or cirrostratus cloud; also known as a mock Sun or sundog. Parhelia appear 22° either side of the Sun, and at the same altitude above the horizon, but disappear when the Sun’s altitude exceeds 60°. Red light is refracted to the edge of the parhelion closer to the Sun, blue to the farther edge. Parhelia are often associated with an atmospheric halo.