Parry & Tangent Arcs

Caught between apartment bocks in Vancouver by Marc Picco.

All images ©Marc Picco, shown with permission
Close-up of the upper tangent and upper sunvex Parry arcs.

The glow of the upper tangent always extends over the Parry arc. The latter is a sub-set of the upper tangent in the sense that Parry oriented crystals are a special case of the singly oriented columns that make tangent arcs.

HaloSim ray tracing to show the Parry arcs in context. At low sun the upper Parry/upper tangent group can be huge.

These arcs change dramatically in appearance as the solar altitude changes.

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