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   Parry Arc II 


Sunvex and suncave Parry arcs.
When the sun is less than 15° high look out for the rare sight of two Parry arcs above the tangent arc.

The uncommon "sunvex" arc, so named because it is convex towards the sun, is best seen at solar altitudes of 7-12°. Its position relative to the suncave arc changes quickly as the sun's altitude alters.

Artist Loren Hall pictured the two arcs on an early spring afternoon in 1991 at Rome, Georgia.

The bright display also had a supralateral arc from singly oriented columns and plate crystals produced a coloured circumzenithal arc. The HaloSim simulation below matched the halos using a solar altitude of 11.7

Photo ©Loren Hall, shown with permission.