9°-parryförmige Bögen (EE66)

At the top and bottom part of the 9° ring, one can observe white light enhancements in rare cases. These are the 9° parry-like arcs, also known as 9° parhelia. They almost always occur alongside other halos created by pyramidal crystals. From a sun elevation of about 30°, the upper of the two arcs can no longer form. The lower arc does not appear above a sun elevation of 50°. In the simulation above, pyramidal crystals with an almost ideally vertical main axis (tilt angle 2°) were used. However, this hardly ever occurs in nature. Therefore, the 9° parry-like arcs are generally seen only as a brightening in the 9° ring and not as an arc bending away from the sun.

The 9° parry-shaped bows form on pyramidal crystals with a vertical main axis. The main axis passes through the two base surfaces. Such crystals are essentially plate crystals with pyramid caps on the base surfaces.