Nacreous clouds over Britain

Dunfermline, Scotland, by Douglas Kerr.
Dunfermline, Scotland, by Douglas Kerr.

Nacreous clouds over Britain

Cloudspotters across the UK and Ireland have witnessed fantastic displays of rare ‘nacreous’ clouds over the first few days of February. The formations are also known as ‘mother of pearl clouds’ due to their beautiful bands of colour, which appear as the cloud’s ice crystals diffract the sunlight, separating it into its different wavelengths. While iridescent colours are seen in many cloud formations, they tend to look much more dramatic in nacreous formations because this cloud’s tiny ice crystals are very regular in size.

Officially known as polar stratospheric clouds, nacreous are typically only observed close to polar regions. They form much higher than most clouds – at altitudes of 10-15 miles (15-25 km), within the stratosphere. They’re only ever observed in winter, when moisture from the troposphere, the lower region of the atmosphere where weather happens, is lifted up into the stratosphere.

The Atlantic storm Henry that passed over Scotland on the 1st and 2nd of February might have contributed to lifting the moisture for these displays. But particularly low temperatures in the stratosphere over the UK have caused the perfect conditions for nacreous clouds. Cold stratospheric air that usually circulates around polar regions, known as the ‘stratospheric polar vortex’, has recently been displaced southwards to extend over the parts of the UK. It has resulted in a nacreous-cloud bonanza for British and Irish cloudspotters. Many fantastic photographs from this sighting have been added to the gallery.

9 Comments
  • kevan

    February 3, 2016 at 9:46 am

    Any from southern England? How far south could you see them?they photos are all from Scotland, northern Ireland, isle of man, northern England and Lincolnshire which I suppose is considered the east Midlands?

  • Gavin Pretor-Pinney

    February 3, 2016 at 1:27 pm

    Kevan,
    We’ve not seen any here in Somerset. There were some sightings around Cambridge on our social media channels, but I’ve heard of none south of there. I guess the stratospheric polar vortex hasn’t stretched further than that.

  • Laurence Green

    February 3, 2016 at 5:07 pm

    Whatever, marvellous displays of a really rare event.

    Laurence

  • Les Cowley

    February 4, 2016 at 8:46 am

    PCSs were seen in Kent and as far south as the French Alps. Pictures at:
    http://www.atoptics.co.uk/fza77.htm
    Les

  • Jo Mildren

    February 5, 2016 at 1:34 pm

    I saw some over Worcester but they were much paler than many photos I’ve seen. I did take photos but they didn’t really show the colours

  • Hozzell

    February 6, 2016 at 2:41 pm

    We had beautiful displays in Bury St Edmunds, Suffolk on the evening of the 1st and both morning and evening of the 2nd. Even managing to watch them till the colour disappeared for the bonus points! I feel very very lucky!

    My apologies if this is not allowed but here is one of the albums of the pictures I took on the 2nd.
    https://www.facebook.com/hazel.murrellwasclarke/media_set?set=a.10208910771150253.1073741939.1344528156&type=3

  • Pete

    February 6, 2016 at 7:32 pm

    I saw some last week in South Hampshire in the New Forest. Unfortunately I did not have camera with me.

  • Gavin Pretor-Pinney

    February 7, 2016 at 11:11 am

    It’s fascinating to see how far they extended. And, Les, the correlation with ozone layer depletion you showed on your Optics Picture of the Day is striking.

  • Simon Welander

    February 9, 2016 at 3:24 pm

    I saw them from Baldock in North Herts, just south of Cambridge and posted a couple of photos. I was lucky to glimpse them through a gap in the cumulus near sunset but they were unmistakable!

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