On Wed, 12 Aug 2015 15:29:05 +0100
"Eskimo Will" wrote:


"Stephen Davenport" wrote in message
...
On Wednesday, August 12, 2015 at 10:10:58 AM UTC-4,
wrote:
"Stephen Davenport" wrote in message
...
On Wednesday, August 12, 2015 at 9:17:11 AM UTC-4, Asha Santon
wrote:
I just made a new photo to replace an old one made by dear mama.

Could some kind person tell me what type of cloud this is?
http://pictures.opcop.org.uk/new99.htm

The sky is full of this type just now and if I know what it is,
I can change the title on the page.
If there's somewhere I can look such things up to avoid
bothering the ng
please do tell.

Thanks in anticipation of someone being nice

========

Altocumulus stratiformis translucidus perlucidus.

Or, given that it is difficult to gauge altitude from a
photograph, possibly high stratocumulus.



Probably Ac I'd say.


Yes, I think so. It immediately looks like Ac but I couldn't
entirely rule out Sc.


Indeed not. Even outside height can be deceptive. I remember one
night shift way back in the 70s as a trainee observer; it was around
dawn and I said to my colleague that there was a bit of stratus
outside. He immediately corrected me and said I don't think so, that
is cirrus s****atus at around 20000 feet! Only 19500 feet out. Air
traffic control would not have been pleased if I had reported patchy
stratus. I was fooled by the fact that the cirrus showed up dark and
was moving quite fast. The CBR was no help (it would not have
recorded cirrus) as the cloud was not over it. When the sun came up,
my error became obvious :-)


While we're on the subject of Ac, I remember seeing a typical "mackerel
sky" one evening about fifty years ago. Typical apart from it being in a
field at about half-a-dozen feet above the ground. I think it may have
been raining earlier and then the sky cleared. I only recently thought
how it had formed and I reckon cold air had rolled down the slope of the
field into a clump of trees at the bottom. A flow of air from the
trees then rolled up the hill creating turbulence at the interface of
the two flows. "Cloud", no more than a foot thick, then formed in the
turbulent layer.

I've seen Ci thicken and darken until it blotted out the sun, having
gone through the As stage where the sun could be seen weakly as through
ground glass. It then developed large, black, ragged rolls like Sc or
St at 800-1,000ft. An aircraft reported the base at 25,000ft with top
34,000.

Nearly fifty years ago, there were reports from Australia of Sc that
was estimated at 4,000ft that turned out to be at 25,000ft. One Sunday
lunchtime, a few weeks after seeing those reports, I saw some Ci Spi
change into what looked like separate Sc or shallow Cu cells at what
might have been estimated to be as low as 3,000ft.

There are more instances of where height estimates by experienced
observers have been out by an order of magnitude, either too low or too
high.

--
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/