Yorkshire's 'upside-down' rainbows

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Media captionThe 'upside-down rainbows' were sighted across Yorkshire on Friday

"Upside-down rainbows" or "smiles in the sky" have been sighted across Yorkshire.

The optical illusion is not in fact a rainbow according to BBC weather presenter Keeley Donovan,

"It is known as a circumzenithal arc," she said, adding: "It is formed when sunlight is refracted through ice crystals rather than raindrops."

Photographs of the spectrum of colours spotted on Friday have been shared on social media.

One BBC Weather Watcher, Mrs D from Glusburn County Primary School near Keighley, said the children had been delighted to see it.

She said: "My class and all the children saw this circumzenithal arc, which appeared just after the Remembrance service we attended in Sutton Park.

"The children were very excited to see a smile in the sky."

Ms Donovan said the meteorological phenomenon usually forms high up in the sky among the cirrus and cirrostratus clouds.

"Although they form fairly frequently, they are usually obscured by layers of clouds beneath, and rarely visible," she added.

Image caption Keeley Donovan said the "smiles from the sky" were usually obscured high in the clouds
Image caption The arc was smiling down on Halifax on Friday
Image copyright WILF BLADE
Image caption It was also pretty clear to see in Sheffield

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