Nacreous cloud has been spotted in Scotland by sky-gazers and is known to be a rare ‘mother-of-pearl’ cloud.
The shimmering colours brightened up the sky on Sunday evening and Monday morning.
Known as one of the highest in our atmosphere – these clouds often come together in cold conditions, BBC reports.
So what are Nacreous clouds?
These clouds take the shape of large, thin discs – reflecting vivid colours.
According to the Met Office, the old English word for “Nacre” means “mother of pearl”.
These rare clouds are known for their coloured light.
“The colours are reminiscent of the colours which reflect from a thin layer of oil on top of the water, an effect known as iridescence,” as stated on the Met Office website.
How do they form?
The clouds form in the lower layer of the earth’s atmosphere – over polar regions when the sun is just below the horizon.
The ice particles then form nacreous clouds, these ice particles are much smaller than those that create normal clouds.
The sun then reflects off of these tiny ice particles, which brings out their pearly streaks – scattering into different colours of light.
The Met Office added: “Due to their high altitude and the curvature of the Earth’s surface, these clouds are lit up by sunlight from below the horizon and reflect it to the ground, shining brightly well before dawn and after dusk.”
Nacreous clouds tend to form in very cold and dry weather conditions and are rarely spotted in the UK.
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Here are some images of the Nacreous clouds:
Image: Hues of red, purple, white and many more colours brighten up the sky. Pic: Victoria Matthews. 
Image: Nacreous clouds over Peterhead. Pic: Steven David McCarron. 
Image: The Scottish Highlands near Invershin. Pic: Alan West 
Image: The colours illuminate Scotland. Pic: Victoria Matthews. 
Image: The sky in Portmahomack, Scotland. Pic: Hannah Rattue 
Image: The Nacreous clouds shone brightly in the sky. Pic: Laura Schofield 
Image: Polar stratospheric clouds, nacreous clouds. Pic: Ceol Mor Highland Lodges 
Image: Nacreous cloud over Aberlour at 4:45pm. Pic: John MacDonald
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