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just to be curious... (22° Halo)

22° halo

A 22° halo (known also as moon or solar halo) is an optical phenomenon, forming a circle with a radius of approximately 22° around the moon or sun, produced by reflected/refracted light interacting with millions hexagonal ice crystals suspended in the cirrus or cirrostratus clouds (troposphere, 6-13 km high).

No light is reflected towards the inside of the ring, giving it the impression of a big hole in the sky. As the sailors says, when the 22° halo appears in the sky, a storm is approaching.

In clear sky conditions the view of this phenomenon is spectacular: the one in the photo (taken in Thaba-Tseka, Lesotho) is a lunar halo, much rarer than the solar halo.