Icebow

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It has been suggested that this article or section be merged into Halo (optical phenomenon). (Discuss)

Halo/icebow with sun dogs visible to the left and right (NOAA)

$Ice-bow around the sun at temperate latitude. Contrast enhanced for clarity. There is also a brighter nearly white diffraction disk nearer the sun, with red on the outside.$

Ice-bow around the sun at temperate latitude. Contrast enhanced for clarity. There is also a brighter nearly white diffraction disk nearer the sun, with red on the outside.

An icebow, also known as a halo, is phenomenon similar to a rainbow except that it is formed by the refraction of sunlight through cloud suspended ice crystals as opposed to raindrops or other liquid water suspended in the air. Generally the appearance is as arc sections as opposed to a full circle. Brighter sections usually occur above, below, and lateral to the center (where the sun is visible). These 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. Those icebows that are caused by very small ice crystals are one color, because diffraction blurs the colors together. A 22 degree icebow has red on the inside and blue on the outside.

A diffraction disc or Airy disc has similar appearance, but is a disk, rather than a ring, and has a red border on the inside. Its size depends on the size of the ice or water particles that cause it. These are also known as coronas, but are not to be confused with the thin streaming luminous gas that makes up the sun's own corona.