This rainbow cloud over Mount Everest took Oleg Bartunov, 51, by surprise. He caught the spectacle on camera during a Himalayas expedition in Nepal. His two images show almost the whole spectrum of the rainbow in a natural event rarely recorded at Mount Everest.
Not every cloud has a silver lining; this multi-coloured cloud looks as if a rainbow has formed high in the heavens. The phenomenom - called a sundog - happens when ice crystals appear in clouds and refract the sun's rays. Photographer Robert Arn captured the cloud in Heyworth, Illinois, America. Picture: Robert Arn/solent