Parhelic Circle

The parhelic circle is a colourless band of light around the sky at the same altitude as the sun. It is colourless because it is caused by reflection off the outer faces of ice crystals. It is not very common as it depends on a high proportion of ice crystals having one face in a vertical position.

There were two bright spots on this bright parhelic circle, each 120 degrees from the sun. Not surprisingly these are called 120 degree parhelia and are caused by a series of reflections within the ice crystals. Complete arcs like this are rare - this is by far the best I've seen.

Although the cirrus was barely visible it produced these colourful sundogs. The 'tails' on the sundogs are the beginning of a parhelic circle which became very strong later on in the display.

Olympus mju 1, 35mm    8th August 1993
Oxfordshire, England

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