They may look like an Impressionist masterpiece, but these rare nacreous clouds have been spotted 'painting' skies above the UK in a rainbow of colours.
Photographers across the north of England and Scotland have captured the stunning 'mother of pearl' formations which sit in the lower stratosphere.
Officially known as polar stratospheric clouds, they are typically seen over Norway and other polar regions when the sun is just below the horizon.
But while they appear beautiful, they are also destructive.
It is thought that recent storms may have increased the chances of the clouds forming over the UK, by driving moisture up into the stratosphere - twice as high as a jet liner flies.
This is where the clouds form, at around 70,000ft (21,336 metres) and in cold air at around -78°C (-108°F). It's also where the ozone layer resides.
The unusual and beautiful sight has also been mistaken by some as aurora borealis, or the Northern Lights.
Their colour comes from ice crystals refracting the sun's rays to give the rainbow effect.
Nacreous clouds have been particularly vivid in Scotland and Northern England before dawn in the past few days.
Professional photographer Alec Jones took some shots of the clouds over Souter Lighthouse near South Shields.
He said: 'These clouds are very rare over England and I've never seen anything like them before. I got up at 5am to wait for the sun to come up so I could get some good photos.'
However, as well as being beautiful, the clouds are destructive and are a large contributing factor in the formation of ozone holes in the polar regions.
While it's usually too dry for ice crystals to develop in the stratosphere, so that few clouds develop, nacreous clouds are different because they are a mixture of cooled water, ice crystals and nitric acid.
Nacreous clouds provide an ideal surface for chemical reactions involving CFC-derived compounds, created by humans that have ended up in the stratosphere.
As the CFC compounds react with the clouds when they are bathed in sunlight, chlorine gas is released, which damages naturally occurring ozone in the atmosphere.
A single chlorine atom is capable of destroying thousands of ozone molecules, meaning chlorine is able to decimate parts of the ozone layer.
Sam Cornwell, a photographic artist based in Hawick on the Scottish Borders, also got some amazing pictures.
The astrophotography teacher at Kielder Observatory, said: 'The clouds were better than any auroras I have ever seen. They were beautiful mother of pearl colours and you could see them with the naked eye.
'I've seen the Northern lights many times, but they were nothing compared to these stunning nacreous clouds.'
Lancaster University's Aurorawatch UK told the BBC it had received reports of the aurora borealis.
But conditions have not been right for the aurora, leading experts to believe people have been mistaking the Northern Lights for nacreous clouds.
Alistair Lockett, from County Durham, said he was amazed by the colour and shapes of the clouds.
He said: 'I've never seen anything like these clouds before, it was incredible. As soon as I saw them I headed to the highest point to get my pictures. It was very windy but absolutely worth it.'
(http://www.dailymail.co.uk/sciencetech/article-3428242/Devastatingly-beautiful-Rare-rainbow-clouds-seen-painting-skies-UK-despite-splendour-formations-cause-holes-ozone-layer.html?ito=social-facebook)
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