The extraordinary sight is a rare cloud formation known as a 'lenticular cloud' - or simply a cap cloud over Klyuchevskaya Sopka mountain in east Russia. The bizarre lens-shaped formation happens when moist air flows over mountains.
The breathtaking shot was taken by keen photographer Ivan Dementievskiy, 35, who captured the stunning moment while on a photo tour in the region earlier this year.
He said: 'I couldn't believe my eyes when I spotted this cloud - it was so special and the people who live near it said they have never seen it before.
'The sky suddenly seemed to open up and this UFO shape appeared. I have been a photographer for more than 10 years and it's one of the few times I have been completely amazed.
'It was one of those moments I'll never forget.'
Lenticular clouds and the turbulence that comes with them are a mixed blessing for aviators.
Pilots of powered aircraft avoid them because of their unpredictability, but glider pilots are attracted to the clouds bacause of the accompanying 'wave lift'.
Rising air mass near lenticular clouds can be both smooth and strong, and the current gliding world records for both distance (1,864 miles) and altitude (50,721ft) were set using such lift.
