Parhelion is an image of the sun often formed when halos intersect, parhelia are hence often called mock-suns. Solar halos are generally considered to be due to refraction and reflection of the sun's rays by ice crystals in the higher strata of the air. Double refraction by the crystals may cause two halos, and reflection from the ice faces may give rise to others, some of these will probably intersect causing a parhelion to be seen. The parhelia are usually brightly coloured like the halo, and are sometimes accompanied by fiery tails. Some very fine parhelia were seen at Brighton on. June 5, 1875.