Circumzenithal arc over Bournemmouth
© Hellyhorro@Twitter
A rare cloud 'phenomenon' was spotted over Bournemouth last week.

The rainbow coloured haze in the cloudy sky led a string of enquiries on social media.

And while many put the colourful sight down to cloud iridescence, some said it could also be a circumhorizontal arc. Cloud iridescence happens when light is diffracted by ice crystals in the clouds, producing a rainbow effect.


Whereas circumhorizontal arcs are apparently formed when the sun is higher than 58 degrees above the horizon. Light is refracted as it passes through high cirrus clouds.

The two, though similar in appearance it seems, are different, although as rare.
Circumhorizontal arc over Bournemouth
© diaryofmrsbrown@twitter
Other readers have got in touch to say they saw a similar cloud formation on May 21.
Circumhorizontal arc over Bournemouth
© Gary Power
If you captured any pictures, send them to digital@bournemouthecho.co.uk and we'll add them to our story.