On Wed, 26 Oct 2016 11:43:59 +0100
"Eskimo Will" wrote:

On another note
big arguments over whether 7/8 Cu should be reported or not when it
was obvious large holes in the cloud field were apparent but little
blue sky visible. Another sticky point was the under-estimating of
cirrus amount, putting dark glasses on usually revealed much more
than reported.

I was told very early in my career that one should never report more
than half-cover of Cu. I didn't agree at first but it was pointed out
to me that one should judge the amount by only including the base of
the cloud in one's estimation of the coverage; the sides of the cloud
should always be counted as being part of the sky, not the cloud. When
I applied that rule and mentally switched the sides of the cloud from
yellow, say, to blue to match the sky, I don't remember ever having to
report more than 4/8 of Cu.

With cirrus being precipitation, should it be counted as a cloud? And
if it is a cloud, isn't snow Cirrus? ;-) The same could be said of As
since that is merely precipitation, perhaps with the Ac mother-cloud
still in existence above it. Ever since I joined the Met Office, I've
been tempted to report low-level Cirrus when I've had decaying snow
showers drifting in from the North Sea and sometimes had half the sky
covered with snow but no reportable clouds. Never had the guts to try
it though; it would have been a waste of effort in any case.

--
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]