LETTER: Beautiful display in evening sky

By The Newsroom
Published 3rd Jul 2014, 07:00 BST
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I wonder if any of your other readers noticed the beautiful circumzenithal arc high in the sky early on the evening of Wednesday, June 25.

This fairly rare ‘upside-down’ rainbow is caused by a refraction of sunlight through horizontally-oriented ice crystals, generally in cirrus clouds. It forms a quarter of a circle centred on the zenith and on the same side as the sun.

Cirrus clouds which cause a ‘sun dog’ can cause a circumzenithal arc when they reach the zenith, if the sun is low in the sky.

V.M. Lloyd (Mrs)

Ash Road, Southwater