Circumzenithal Arc Sequence

This sequence of images over about one minute shows just how quickly the circumzenithal arc can change appearance. This isn't a great surprise since it is very dependent on the shape of the ice crystals and their orientation. The cirrus was quite patchy anyway.

The two long streaks of cirrus left of centre don't show any sign of colour so their ice crystals weren't in the right state. The arc formed briefly several times over about half an hour, but never lasted more than a few minutes. The cloud forming the arc moves upwards during this sequence.

Pentax Optio S40   21st August 2004
Buckinghamshire, England

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