Circumhorizontal Arc
A Circumhorizontal Arc
A circumhorizontal arc is an optical phenomenon - an ice-halo formed by the refraction of sun- or moonlight in plate-shaped ice crystals suspended in the atmosphere, typically in cirrus or cirrostratus
clouds. In its full form, the arc has the appearance of a large,
brightly spectrum-coloured band running parallel to the horizon, located
below the Sun or Moon. It can be caused by...
