Subparhelic circle

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A photo centred on the antisolar point featuring various antisolar haloes as viewed from a flight between Brussels and Madrid, August 07, 2006.
Photo: Francesco De Comité.

The subparhelic circle is a rare halo, an optical phenomenon located below the horizon. It passes through both the subsun, below the sun, and the antisolar point, opposite to the sun. The subparhelic circle is the subhorizon counterpart to the parhelic circle located above the horizon.

Located on the subparhelic circle are several relatively rare optical phenomena: The subsun, the subparhelia, the (still undocumented) 120° subparhelia, Liljequist subparhelia, the diffuse arcs, and the Parry antisolar arcs. ^[1] ^[2]

On the accompanying photo centred on the antisolar point, the subparhelic circle is viewable as a gently curved horizontal line intercepted by anthelic arcs. ^[3]

[edit] References

^ Les Cowley. Subhorizon Arcs. Atmospheric Optics. Retrieved on 2007-04-21. (including a computer simulation.)
^ Les Cowley. Antisolar Region Arcs. Atmospheric Optics. Retrieved on 2007-04-21. (including a photo and a computer simulation.)
^ Jarmo Moilanen. Subhorizon diffuse arcs with Liljequist subparhelia. Halo Reports (Blogspot). Retrieved on 2007-04-21.