Subhorizon Gems

Rarely seen subhorizon halos imaged by Gabor Pete over the Gulf of Riga.

 All images ©Gabor Pete shown with permission
A HaloSim ray tracing of the display. The corresponding above horizon arcs - invisible in reality for lack of cloud - automatically show up .
Atmospheric
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At left is perhaps the rarest sight of all - a 120° subparhelion.

Plate crystals form 120° parhelia. For bright ones the plates need to be rather thick or of triangular aspect to permit the ray with internal reflections from adjacent side faces.

An additional internal reflection from the lower basal face produces the subparhelion.
         
 
Halos below the horizon are mostly the result of an extra reflection within each halo forming crystal.

A subparhelic circle crosses the top image. Its brightenings at left and right are sub-Liljequist parhelia formed by plate crystals.












At image centre the cross is (it is always hard to identify the main contribution) some combination of a Parry antisolar arc (Parry oriented columns)...











     ....and 'diffuse arcs' from ordinary singly oriented columns.