Parry Orientation
This system consists of column crystals oriented with the optical axis and two faces at or near horizontal with respect to the ground. The figure below simulates 75% parry oriented crystals of varying size and a 25% random hodgepodge of ice crystals. In the following figures the Parry arcs are labeled. The naming convention is sunvex if the arc is convex with respect to the sun and suncave if the arc is concave with respect to the sun. These arcs are very rare due to the orientation required. At 10 degrees you also see 46 degree supralateral arcs on either side.
Figure 1:Parry crystal halos at 10 degree sun elevation. Image created using HaloSim3 developed by Les Cowley and Michael Schroeder and available at http://www.atoptics.co.uk
 |
Figure 2:Parry crystal halos at 60 degree sun elevation Image created using HaloSim3 developed by Les Cowley and Michael Schroeder and available at http://www.atoptics.co.uk
 |
At 60 degrees both suncave arcs are clearly visible with nice color separation.