Winter Circumzenithal Arc
captured by Mark Damato.  İMark Damato, shown with permission.

The low sun of winter offers more opportunities to see fine CZAs and sundogs.

For a CZA to be seen the sun must be lower than 32° and an altitude between 15 and 25° is best.

Six sided plate shaped ice crystals drifting with their large faces nearly horizontal produce the arc.

The crystals may be in high cirrus cloud or much closer in low level diamond dust.

Atmospheric
Optics

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