On Tue, 25 Oct 2016 18:32:39 -0000
"Bernard Burton" wrote:

On the 10th October 2016 a sheet of stratiform cloud was producing
fall-streak holes over southern UK. Howerver, holes developed in
certain parts of the sheet only. An analysis of the available data
indicates that the cloud was at a height near 25000 ft, and at a
temperature of -31 C, and its unusually cold temperature holds the
key to the unusual nature of this cloud.

http://www.woksat.info/wwp/cloud-161010-final.pdf


Just had a quick glance through [I'll take a longer look tomorrow] but
the idea that -31C is unusually low for water droplets to occur in
clouds surprised me a bit. Nearly fifty years ago, I read that a
research aircraft had found water droplets at a temperature of -60C.

Just as a switch, I've also seen ice-crystal cloud (Ci Spi) seem to turn
into water-droplet cloud but that's another story.

--
Graham P Davis, Bracknell, Berks. [Retd meteorologist/programmer]
Web-site: http://www.scarlet-jade.com/
There are more fools than knaves in the world, else the knaves would
not have enough to live upon. [Samuel Butler]