On Tuesday, February 2, 2016 at 11:20:31 AM UTC, Martin Brown wrote:
On 01/02/2016 18:14, Col wrote:
On 01/02/2016 18:11, 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


Saw something very similar here towards the west.

Still visible this morning in North Yorkshire. They look like they are
nacreous clouds from the sculpted shapes and strong irridescence.

It appears the strong winds have punched some water vapour up into the
stratosphere. I watched them evolving as it grew light this morning.

Pictures will follow shortly.

Still visible (just) in daylight at the moment 11am 2/2/16.

Low fast moving clouds interfering slightly just as they did in the
previous widespread display of Feb 16 1996. Conditions were as I recall
somewhat similar with a very strong surface winds although the clouds
this time were not as obviously lenticular in nature.

http://www.nezumi.demon.co.uk/nacreous/nacreous.htm

(previous display of 1996)

--
Regards,
Martin Brown

Just shows the importance of observation and keeping your head up. Just returned from my morning walk, but I was head down into the wind and never thought they might still be around and too many clouds scudding through on the wind now to be able to see owt!

On Tuesday, February 2, 2016 at 12:11:50 PM UTC, Freddie wrote:
Martin Brown Wrote in message:
On 01/02/2016 18:14, Col wrote:
On 01/02/2016 18:11, 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


Saw something very similar here towards the west.

It appears the strong winds have punched some water vapour up into the
stratosphere.
I think they have formed because the stratosphere is much colder
than normal at the moment, rather than additional water vapour
being added to it.

--
Freddie
Pontesbury
Shropshire
102m AMSL
http://www.hosiene.co.uk/weather/
http://twitter.com/PontesburyWx for hourly reports


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

Yes Martin they are still there. Skies have cleared somewhat and with them being in the Southern half of the sky and a low sun, they are quite hard to spot, unless you know they're there.

Martin Brown Wrote in message:
On 01/02/2016 18:14, Col wrote:
On 01/02/2016 18:11, 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


Saw something very similar here towards the west.

It appears the strong winds have punched some water vapour up into the
stratosphere.
I think they have formed because the stratosphere is much colder
than normal at the moment, rather than additional water vapour
being added to it.

--
Freddie
Pontesbury
Shropshire
102m AMSL
http://www.hosiene.co.uk/weather/
http://twitter.com/PontesburyWx for hourly reports


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

On 02/02/2016 12:23, David Mitchell wrote:
On Tuesday, February 2, 2016 at 12:11:50 PM UTC, Freddie wrote:
Martin Brown Wrote in message:
On 01/02/2016 18:14, Col wrote:
On 01/02/2016 18:11, 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


Saw something very similar here towards the west.

It appears the strong winds have punched some water vapour up into the
stratosphere.

I think they have formed because the stratosphere is much colder
than normal at the moment, rather than additional water vapour
being added to it.

I think it requires both conditions to be met before you see any. The
stratosphere is normally too dry for PSCs to form even when cold enough.

Incidentally the ozone levels over Uccle have crippled by 100 DU in the
last few days so it is definitely widespread and stratospheric clouds.
It is only about 20 away from hitting their lowest baseline of 200DU.

http://www.meteo.be/meteo/view/nl/12...ratosfeer.html

I presume the location of the most visible clouds is related to the
structure of lee waves from the Pennines.

Yes Martin they are still there. Skies have cleared somewhat and with
them being in the Southern half of the sky and a low sun,
they are quite hard to spot, unless you know they're there.

They were still fairly colourful - especially on the leading edge at
lunchtime but have been thickening up since then and are now a mottly
white with hints of colour but still obviously sculpted by the wind.

I am hoping they will persist into the evening when I will be able to
take some better pictures with a proper camera and tripod rather than
handheld from a moving car with a mobile phone.

I was amazed when I spotted them early this morning.

--
Regards,
Martin Brown

I am hoping they will persist into the evening when I will be able to
take some better pictures with a proper camera and tripod rather than
handheld from a moving car with a mobile phone.

I was amazed when I spotted them early this morning.

--
Regards,
Martin Brown

I was hoping as well, but there's some cirrus around now rather obscuring the view.

On Mon, 1 Feb 2016 13:08:04 -0800 (PST)
Stephen Davenport wrote:

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

========

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



Although one name for these is Polar Stratospheric Clouds it may be
time to drop that. One of the predicted effects of global warming that
was made at least forty years ago was that the stratosphere would cool
most rapidly in the Tropics. A report I saw a couple of years or so
ago said that cooling of 8C had been recorded.

A while ago, I came across a report of iridescent clouds in Central or
tropical South America that someone thought might be nacreous clouds. I
checked the local ascents and found the temperatures were just about
low enough in the stratosphere for that to be possible. I don't think
they were nacreous clouds but I think it's just possible that they may
be seen anywhere.


--
Graham P Davis, Bracknell, Berks. [Retd meteorologist/programmer]
http://www.scarlet-jade.com/
I wear the cheese. It does not wear me.
Posted with Claws: http://www.claws-mail.org/

On Tue, 2 Feb 2016 17:10:25 +0000
Graham P Davis wrote:

On Mon, 1 Feb 2016 13:08:04 -0800 (PST)
Stephen Davenport wrote:

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

========

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



Although one name for these is Polar Stratospheric Clouds it may be
time to drop that. One of the predicted effects of global warming that
was made at least forty years ago was that the stratosphere would cool
most rapidly in the Tropics. A report I saw a couple of years or so
ago said that cooling of 8C had been recorded.

A while ago, I came across a report of iridescent clouds in Central or
tropical South America that someone thought might be nacreous clouds.
I checked the local ascents and found the temperatures were just about
low enough in the stratosphere for that to be possible. I don't think
they were nacreous clouds but I think it's just possible that they may
be seen anywhere.



And, hot off the presses, here's a blog from the Met Office with
explanations and some more pretty pictures:

http://blog.metoffice.gov.uk/2016/02...l-skywatchers/

--
Graham P Davis, Bracknell, Berks. [Retd meteorologist/programmer]
http://www.scarlet-jade.com/
I wear the cheese. It does not wear me.
Posted with Claws: http://www.claws-mail.org/

Yes, they were still here in East Scotland, in exactly the same place, this morning.

David you have my sympathy. It's usually me walking around with my head down. Fortunately they were floating just above my iMac in my study ...

On Tuesday, February 2, 2016 at 6:15:06 PM UTC, Trevor Harley wrote:
Yes, they were still here in East Scotland, in exactly the same place, this morning.

David you have my sympathy. It's usually me walking around with my head down. Fortunately they were floating just above my iMac in my study ...

That's a big iMac you have Trevor!

"Graham P Davis" wrote in message
-jade...
On Mon, 1 Feb 2016 13:08:04 -0800 (PST)
Stephen Davenport wrote:

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

========

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

A while ago, I came across a report of iridescent clouds in Central or
tropical South America that someone thought might be nacreous clouds. I
checked the local ascents and found the temperatures were just about
low enough in the stratosphere for that to be possible. I don't think
they were nacreous clouds but I think it's just possible that they may
be seen anywhere.


--
Graham P Davis, Bracknell, Berks. [Retd meteorologist/programmer]
http://www.scarlet-jade.com/
I wear the cheese. It does not wear me.
Posted with Claws: http://www.claws-mail.org/


That is a difficult observation Graham, one I would question.
I spent some years in the tropical Pacific in Vanuatu (17S 168E) flying
sondes. The temperature at the tropopause sometimes got as low as -85C, but
always rose quite rapidly as you went into the stratosphere, reaching
ca. -30C near 10 mbar. Our ascents reached between 34 and 36 km regularly,
where the temperature could be as high as -15C, but I can't recall ever
seeing a secondary temperature minimum above the tropopause.The trop. was
always higher (above the ground) than 150 mbar, and could be as high as 90
mbar on occasions. I observed (on radar) a Cb top reaching 18 km, 2 km above
the trop on that day, and would have had an in-cloud temperature well
below -90C. Iridescence was not infrequent near sunrise/sunset, but was
always (in my experience) tropospheric cloud, albeit high. The -40C isotherm
was often near 10km, so thin Ac cloud could occur up to 30000 ft plus at
least. High, sometimes thin, cirrus could sometimes be seen near the trop.
at dawn/dusk, but was mostly Cb debris, although the sub-tropical jet could
sometimes buckle enough to allow jet-stream Ci/Cs to appear at 17S., but
this was usually much thicker and chunkier looking, and both didn't produce
iridescence.

--
Bernard Burton

Wokingham Berkshire.

Weather data and satellite images at:
http://www.woksat.info/wwp.html