Rare 'rainbow clouds' spotted across Yorkshire
Rare rainbow-effect cloud formations have brought a colourful display to the skies across Yorkshire.
Nacreous clouds usually form in very cold conditions over polar regions and within the stratosphere, far above our normal clouds.
One of the highest clouds, they are often referred to as "mother-of-pearl" formations.
They are rarely spotted in the UK because of the exceptional conditions needed.
BBC Weather Watchers and social media users shared images of the clouds, which were spotted across West, South and North Yorkshire.
The phenomenon had previously been seen across other parts of the UK on Tuesday.
Polar vortex
Nacreous cloud is mostly seen a couple of hours either side of sunset or sunrise.
Occasionally, cold polar air which is locked in place by strong winds high up in the atmosphere - called the polar vortex - sinks south to our latitude.
Formed at heights of around 12-19 miles (19-31km), in air that is about -80C (-112F), tiny ice crystals refract sunlight, giving the cloud its pearly colours.
Being so high, it is still lit by sunlight which makes it appear even brighter in the sky.
Because of the height and temperature needed, it is also known as Polar Stratospheric Cloud.
It is more commonly seen in places like Scandinavia and Canada.
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