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"Eye in the Sky display", Germany, October '08 by Claudia Hinz (Atmospheric Optics site). ©Claudia Hinz, shown with permission.

The "eye" is formed by a rare Parry arc atop an upper tangent arc. Both are formed by column crystals but those making the Parry are more restrictively aligned with two side faces nearly horizontal.

A sundog from plate crystals is at lower right but unusually, there is no 22° halo.

Both the Parry and upper tangent arcs alter their appearance with solar elevation. The HaloSim ray tracing simulations show the changes. As the sun climbs the gap between the two arcs narrows. The parry arc is always the sharpest and has the purer colours.

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