Martin Rowley wrote:

On 15/11/2012 10:23, Bernard Burton wrote:
"Martin Rowley" wrote in message
...

... using this site:-

http://www.sat24.com/

choose VIS imagery for Europe and you can see (now the sun is illuminating
the cloud tops) a near-perfect arc of line convection with (I think) just
one break. Seems to be coming forward associated with cyclonically-sheared
development associated with the slow-moving/warming-out vortex seen here
...

http://www.wetterzentrale.de/pics/Rtavn001.png

Martin.


--
West Moors / East Dorset
Lat: 50deg 49.25'N, Long: 01deg 53.05'W
Height (amsl): 17 m (56 feet)
COL category: C1 overall

The band of activity also seems to be linked to the region of strong
diffluence near the axis of the jet on the southern side of the upper
vortex, also linked to a short-wave trough rotating the vortex.
http://www.wetterzentrale.de/pics/Rtavn0015.png


... thanks for that Bernard: a fascinating feature and demonstrates once
again the beauty of the atmosphere!

And we've even had a single sferic out of it - which I have to admit I hadn't
expected after my second post on the subject - but I would have done after
the first!

Collapse of stout party :-)

Martin.

I had occasion to investigate this sort of feature in some detail a while ago -
Bernard may remember the event, which I discussed with him. I located a few
papers (including a couple in 'Weather') dealing with these very distinct and
persistent lines of vigorous but relatively shallow convection. They sometimes
produce rainfall intensity and squalls out of proportion to their vertical
development. Radar imagery and sometimes visible wavelength satellite imagery
give a completely different impression to that gained from IR satellite
imagery. If reliance is placed solely on radar imagery it is very easy to be
misled into thinking that the imagery is the result of a line of Cb.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.