Halo

Halo is a ring of light that surrounds the sun or moon. The halos form between 5 and 10 kilometers in the upper troposphere. The shape and orientation of ice crystals from the highest clouds are responsible for the type of halo observed. Light is reflected and refracted by ice crystals and can be divided into colors because of the rainbow-like scatter. The main types of halo are 22º halo, 46º halo and circumscribed halo (or tangent arc).

Halo 22°: circle around the Sun or Moon. This type of halo forms when the sky contains millions of misguided ice crystals. Some of these are aligned perpendicular to sunlight for one observer, while other crystals are aligned for another observer; that is, two people do not see the same halo. Like other ice halos, 22 ° halos appear when the sky is covered by thin Cirrus or Cirrostratus clouds containing the ice crystals that make the phenomenon happen.

Halo 46°: The formation of the halo 46º is very similar to that of the 22º halo. Crystals should have random orientations in the cloud, as should the 22 ° halo. Thus, in reality, the 46th halo will almost always be present when the 22nd halo is present, but rarely is it seen. One reason is that there may be no cloud where the halo should be, but the main reason is that this halo is wider than 22º, causing its colors to spread more, making it weaker. In addition, there are fewer crystals contributing to the formation of this halo compared to 22 °.