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Tangent Arcs

Tangent arcs vary with solar elevation. They always touch the 22° halo. When solar elevation increases, the tangent arc becomes flatter and larger. At 29°, the two upper wings are bent down and form a circumscribed halo. The circumscribed halo is often not complete so that barely an arc bent down on both sides is visible.
There always is a bright whitish zone above the upper and below the lower tangent arc in the region where they touch the 22° halo. Tangent arcs and circumscribed halos can get very bright and often show intense colours.

Upper tangent arc on January 9th, 2005. Canon Powershot G6, processed with Adobe Photoshop Elements.

Typical fragment of a circumscribed halo at a solar elevation of 44.7. Canon Powershot S80, processed with Adobe Photoshop Elements.