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   Circumscribed Halo - solar altitude 

Upper and lower tangent arcs and a faint 22º halo. HaloSim3 simulation. The region below the horizon is dark blue.  
Changing shape of the circumscribed halo with solar altitude. Mouse slowly over the slider to see the changes.

The halo "starts" at a sun elevation of 29º as the joined form of the upper and lower tangent arcs.

It has a pronounced drooping distorted oval shape until the sun reaches ~50º high. Often only the brighter upper and lower sections are visible.

When the sun is higher, the halo approaches the 22º halo more and more closely and it becomes exactly circular when the sun is overhead.

At high sun it is not easy to tell the circumscribed and the 22º halos apart.

The circumscribed halo has somewhat brighter and purer colours because rays through the singly oriented columns producing it give less colour overlap than those through the much less oriented crystals making the 22º halo..