S Korea Halos ~ Heesang Yoo caught this unusual pair of high sun (summer) ice halos in April '11.  ©Heesang Yoo

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The display is unusual because it shows two halos that when seen individually are difficult to distinguish from one another.

The halos are directly beneath the sun.  They are a first glimpse of summertime halos because they both require the sun to be higher than 58°.   

The lower of the arcs is a circumhorizon arc produced by hexagonal plate shaped crystals drifting in cirrus with their large faces very nearly horizontal.   Rays enter a vertical prism side face and leave through the lower hexagonal face.   The refraction and dispersion through facets at 90° to each other gives wide colour separation.

The other halo touching the circumhorizon arc at right but curving upwards and away from it at left is possibly seen less often. It is an infralateral arc produced by hexagonal column crystals drifting with their long axes horizontal.   Rays enter a prism end face and leave through a lower side face.   The refraction is again through facets inclined at 90°.

Evidence for the column crystals is provided by the two lower images that show halos closer to the sun where a circumscribed halo also produced by columns is prominent.

The matching HaloSim ray tracing shows the positions of the halos relative to the sun and horizon.   The circumhorizon arc is at a constant altitude above the horizon, the infralateral arc curves upwards each side of the sun. A very colourful arc beneath the sun might be either.