LONDON -- If you happen to have looked up into the sky recently and spotted strange patterns of shifting colours, don't panic -- the weird bodies of lights appearing above Britain aren't UFOs, they're nacreous clouds.
The Met Office took to Twitter on Tuesday morning to share an image taken by Lea Harris of the sky over Edinburgh, UK.
Unusual #nacreousclouds spotted across the UK. How do they form? https://t.co/iFvb915UQL (pic:@BakersBunny) pic.twitter.com/AzcjkD6WdW— Met Office (@metoffice) February 2, 2016
Harris wasn't the only one to spot the unusual clouds.
Very beautiful #nacreousclouds from the herbarium this morning pic.twitter.com/p0wrKPAOIN— RBGE_Herbarium (@RBGE_Herbarium) February 2, 2016
More of those crazy clouds this morning #nacreousclouds #northumberland #StormHenry pic.twitter.com/bfeIEzr1jb— Anita Nicholson (@AnitaNicholson) February 2, 2016
Hi @barrabest - caught some #nacreousclouds this morning in Belfast @metoffice @BBCnireland pic.twitter.com/ReHDsokKH6— Neil Hutcheson (@zutch) February 2, 2016
So what exactly are nacreous clouds, anyway?
According to the Met Office, they're basically clouds that have been lit up with luminous light from below. The clouds are usually found in Northern countries during polar winter when the sun is hanging low in the sky, and their rainbow-like appearance has earned them the nickname "mother of pearl clouds".
Cannot believe how beautiful the sky is this morning @STVEdinburgh @edinburgh @BBCRadioScot pic.twitter.com/nYEHI7ohqM— Lea Harris (@BakersBunny) February 2, 2016
@AnitaNicholson @RTalibart Seen yesterday evening in Wigan too!! Amazing!! #nacreousclouds pic.twitter.com/UIPtVUEzYt— John Barton (@JodBart) February 2, 2016
Spectacular #nacreous clouds over south #Edinburgh this morning @bbcweather @BBCScotWeather Hat tip to @anghyflawn pic.twitter.com/UslgQfRWyV— Warren Maguire (@warren_maguire) February 2, 2016
The sky did it again this morning so incredibly beautiful. Been watching this for about an hour. #nacreousclouds pic.twitter.com/kNRTG9mxix— Charlotte Brown (@lottibdesigns) February 2, 2016
Amazing #nacreousclouds again this morning...I'm in love @edinburgh @bbcweather pic.twitter.com/Odf0WpBUjG— Rhona Christie (@RhonaChristie) February 2, 2016
#nacreousclouds as seen over West Lothian Scotland this morning. @bbcweather @metoffice @JournoandGaz #StormHour pic.twitter.com/NxxXZTNwVJ— James C Smith (@JC_Image) February 2, 2016
#nacreousclouds over Grantham today pic.twitter.com/98mcUmU8r3— jim linning (@jimlinning) February 1, 2016
Mashable has reached out to the Met Office for more information on the clouds' appearance over Britain, and we will update this article when we receive a response.
UPDATED 16:45 2 FEBRUARY: The Met Office have contacted Mashable with more information about the clouds.
"Currently, we are able to catch sight of them because cold air which usually circulates around polar regions in the stratosphere (the stratospheric polar vortex) has been displaced from its usual position over the north pole to be over the UK," a Met Office spokesperson said.
"Our weather forecast models indicate the cold polar vortex will remain nearby for the next few days, so we should be able to see Nacreous Clouds when the skies are clear.
"The position of the vortex shifts towards the end of the week taking the coldest air, and the Nacreous Clouds, away from above the UK."