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Nacreous Clouds

Nacreous Clouds

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    • February 7, 2015 at 3:50 pm #76767
      Ian Loxley avatarIan Loxley
      Moderator

      I have recently been having a chat about an Atmospheric Optic matter http://atoptics.co.uk/ with Les Cowley, he mentioned we are in the middle of the UK season for Nacreous clouds, any sightings please post and send for the gallery.

      http://www.atoptics.co.uk/fz853.htm

      http://www.atoptics.co.uk/highsky/nacr1.htm

      Spotted over Lincolnshire in 1996. http://bit.ly/1vxzEsf

    • February 13, 2015 at 11:36 pm #77012
      Howard Brown avatarHoward Brown
      Participant

      Very interesting… My 1969 RK Pilsbury says ‘Only in Scotland’ (in the UK). atopics says ‘At least twice since 1996’ in England and shows 29JAN2000 – did he know from Ian of the FEB1996 Lincs picture one wonders.

      ‘As rare as nacreous in England’…

      • February 14, 2015 at 11:53 pm #77031
        Howard Brown avatarHoward Brown
        Participant

        The Met Office ‘Cloud types for Observers’ 1982 also does not mention England specifically, and says ‘They are ignored when assessing CH and C’ (cloud classification codes). They are observable before dawn, of course, for early risers (see CAS Calendar for Jan and Feb).

        From the ICA you should look out for ‘…periods with a strong, broad, deep and homogeneous westerly to north-westerly current’.

    • February 19, 2015 at 8:20 am #77223
      Graham Davis avatarGraham Davis
      Participant

      Nacreous clouds are said to form in the stratosphere when temperatures fall below -78C. As one effect of increased CO2 is the cooling of this layer, I think it is possible that Nacreous clouds will become more common. Also, the effect of climate change on the stratosphere is stronger towards the Equator than the Poles, with observed cooling of as much as 8C in the Tropics. This suggests to me that this cloud may become a global feature rather than a largely Polar one.

    • March 2, 2015 at 9:44 pm #77549
      Bill Ward avatarBill Ward
      Participant

      Hi,

      This is the only time I’ve seen nacreous clouds. Not much iridesence but very bright.
      Taken at 16.23UT on 22/12/01. At my latitude ~55 deg 39 min north, sunset was at 15.51UT (basically the winter solstice). Sun was 4 degrees below the horizon at this time.

      Nacreous clouds. Dec 2001.

      Image is a scanned photograph, can’t find the negatives!

      The display caused quite a still amongst local cloud spotters at the time!

      Cheers,
      Bill.

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