On Monday, February 1, 2016 at 1:11:06 PM UTC-5, Trevor Harley wrote:
Behind the view of flying trees and roofs there was quite a good display of iridescent (I think they are) clouds this evening.

http://trevorharley.com/trevorharley/Weather.html

Trevor
The Sidlaws, NW of Dundee

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These are polar stratospheric clouds (PSCs), a.k.a. nacreous clouds. My news and social feeds are full of pictures of them remarkably far south (Buckinghamshire, for example). Or perhaps not so remarkably when you look at how very cold (and moist) the stratosphere is over the UK due to circumpolar vortex displacement (in turn due to ongoing stratospheric warming Pacific-side). Temperatures are between -80 and -85C at 50hPa, for example, and below -85C at 30hPa (and PSCs form below -78C):

http://users.met.fu-berlin.de/~Aktue...ecmwf50a12.gif

http://users.met.fu-berlin.de/~Aktue...ecmwf30a12.gif


Stephen.