"James Brown" wrote in message
...
If you look at one of the satellite visual channels you'll see a pool of
what looks like fog, but with an almost circular surround of small clouds
a distance out from the centre. Not seen that before.

Cheers
James

Yes, that is an interesting observation. It reveals a good deal of
meteorology going on there. The area containing fog/low cloud inhibits
diurnal temperature rise due to reduction in short-wave radiation reaching
the ground, but mainly due to the energy used to evaporate the cloud reduces
that left for sensible heating. The surrounding area receiving the full
whack of insolation will, hour for hour, be warmer than the cloudy area,
allowing convection to set in, albeit of limited depth under the
anticyclonic inversion. The temperature difference plus convection = a
sea-breeze like circulation, and this is what you see on the sat image as a
ring of enhanced convection surrounding what is eventually a cloud free zone
where the fog/low cloud had been earlier.

--
Bernard Burton

Wokingham Berkshire.

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