Rare clouds make Yorkshire sky look like cotton wool - BBC News

Rare cirrocumulus floccus clouds are seen across Yorkshire.

Lenticular cloud: Incredible rare cloud formation looks like a UFO! - BBC Newsround

Rare rainbow-coloured nacreous clouds seen across Yorkshire

In pictures: Rare 'rainbow cloud' seen above the East Midlands - BBC News

Kelvin-Helmholtz: Rare wave clouds amaze sky-watchers in Wyoming

Cotton wool clouds hi-res stock photography and images - Alamy

Rare 'rainbow cloud' dazzles skies across North West - BBC News

VIDEO: Strange cotton wool clouds stun Argentine residents

Rare 'rainbow cloud' dazzles skies across North West

Fallstreak hole: Rare cloud formation pictured in the East