The circumhorizontal arc is a beautiful, large, rainbow-coloured halo and is rarer than other haloes formed by atmospheric ice crystals,
such as sun dogs or the common 22° halo. For it to appear, the sun has to be very high in the sky, with an angle of approximately 58° or higher.
In northern latitudes, the sun only reaches such an elevation for a few days of the year (around mid-summer) during the hours around noon.