|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.