This phenomenon was very prevalent in this area of Berkshire in the 1970s
and 80s. I wrote a note on it in the Journal of Meteorology Apr 1976, p232.
It was sometimes very evident when travelling through Bracknell by train, as
the lying 'snow' from the ice crystal deposit was 0.5 to 1 cm thick in
specific areas, with none at all in other locations close by. On one
occasion I collected a sample of the crystal deposit and sent it for
analysis to try to determine the likely nucleation agent, but the analysis
found only standard pollutants. I also requested a list of chemicals being
discharged from industrial premises in Bracknell from the local council, but
was refused this information.
On another occasion the fog was thin enough to show the sun shining fairly
brightly, and a strong 22 deg halo was present as the crystals were falling.
Another occasion at night showed light pillars above all street lamps and
car headlights in fog with an air temp just below zero, and ice crystal
precipitation occurring.

--
Bernard Burton
Wokingham, Berkshire, UK.

Satellite images at:
www.btinternet.com/~wokingham.weather/wwp.html
"Colin Youngs" wrote in message
...
Tienen - east of Brussels - reported about 1 cm snow on Monday.

Tienen is well-known for its large sugar factory. The effect of the
extra
water vapour released into the atmosphere by the factory and the
prevailing
freezing fog led to the snowfall. A similar phenomenon occurred in
places
in Germany.

Colin Youngs
Brussels