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   Antisolar Region Arcs

Arcs around the antisolar point.

An amazingly bright and rare display seen by Virginia meteorologist Jacob Klee on a flight from Cincinnati to Richmond Virginia during the afternoon of 12th November 2000.

The camera points downwards. The horizon is hidden by the cirrus haze in the topmost quarter of the image.

The antisolar point, the point diametrically opposite the sun, is at the bright diamond with the aircraft's shadow in its centre. The horizontal halo passing through the antisolar point is a bright subparhelic circle.

The diagonal cross is a combination of diffuse arcs from horizontal column crystals and an antisolar arc from Parry oriented columns.

The arcs are labeled in the simulation below.

 

  
Simulation for the solar elevation of 13.5 estimated from the flight times and fits to the photograph. The imaged area is within the blue rectangle. The Parry antisolar arc extends upwards from the antisolar point to form the two outermost parts of the diagonal cross.

The subhorizon arcs in the antisolar region are much narrower than their above horizon counterparts and remain narrow even when the crystal tilts are quite large.

The simulation used 70% singly oriented column crystals, 15% Parry oriented columns and 15% horizontal plates. The columns had c/a ratios of 1-3 and tilts from 0.5 to 5.