Martin Rowley wrote:

"Martin Rowley" wrote ...
... just looked up the WMO catalogue for w'w' (present weather for a
METAR) and I'm pretty sure that this use is incorrect. 'VA' is listed in
the column for 'obscuration', i.e., meteors causing marked reduction in
visibility. The report has VVVV = 9999 (10km or more), and as such doesn't
require a present weather. I suspect they are looking at what we are
seeing elsewhere (haze, whether surface based or elevated).


... forget that: I'm wrong and they are right; VA (volcanic ash) is to be
reported whenever observed. Have now had time to delve deeper into the regs.
Whether it's possible to distinguish such at a great distance from the source
is another matter of course.

Martin.

Although I didn't do so I reckon that reporting the present weather here as VA
would have been justified yesterday. The visibility was certainly reduced by
particles in suspension. The deposit on smooth surfaces was dark grey dust that
sparkled in the sunshine and felt very abrasive. Last night while I was walking
our daughter's dog along dark country lanes I was very surprised by the
concentration of particles visible in a vertical torch beam. The particles
glinted in the beam, much like they had sparkled in the sun. The RH at the time
was around 70 percent so there's no possibility that it was water droplets. No
deposit to be seen this morning, though. The rain has washed it all away.

Norman

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