Or do we call it snow? A covering of ice needles here in Farsley near Leeds
Temperature down to -4C already at 6pm in mist/fog. Surprisingly the same
event occured on 19 February here in Leeds and Wakefield areas when
measureable depths were reported.

"Rob Brooks" wrote in message
...
Or do we call it snow? A covering of ice needles here in Farsley near
Leeds
Temperature down to -4C already at 6pm in mist/fog. Surprisingly the same
event occured on 19 February here in Leeds and Wakefield areas when
measureable depths were reported.


This was mentioned by Steve (Willington) during his briefing last night with
a view to it not being inconceivable that we could see something similar
again today, particularly downwind of power stations. Could've had Ladbrokes
shaking in their boots with their 12/1 offer on snow today..

Jon.

Jon
Wind has been from a north or northwest point today, so no power stations up
wind: I think fluctuations in the depth of cloud which ties in with small
changes in temperature throught the day.
"Jon O'Rourke" wrote in message
...
"Rob Brooks" wrote in message
...
Or do we call it snow? A covering of ice needles here in Farsley near
Leeds
Temperature down to -4C already at 6pm in mist/fog. Surprisingly the same
event occured on 19 February here in Leeds and Wakefield areas when
measureable depths were reported.


This was mentioned by Steve (Willington) during his briefing last night
with
a view to it not being inconceivable that we could see something similar
again today, particularly downwind of power stations. Could've had
Ladbrokes
shaking in their boots with their 12/1 offer on snow today..

Jon.

This was mentioned by Steve (Willington) during his briefing last night
with
a view to it not being inconceivable that we could see something similar
again today, particularly downwind of power stations. Could've had
Ladbrokes
shaking in their boots with their 12/1 offer on snow today..

Jon.

Hi Jon,
most of the Wirral is being covered by these ice needles this evening and it
looks like it is going to be a white New Year around here :-)
best regards,
Alan

"Rob Brooks" wrote in message
...
Or do we call it snow? A covering of ice needles here in Farsley near
Leeds
Temperature down to -4C already at 6pm in mist/fog. Surprisingly the same
event occured on 19 February here in Leeds and Wakefield areas when
measureable depths were reported.


This effect is due to the freezing of supercooled fog droplets due to the
presence of 'ice nuclei' contaminants in the lower atmosphere. The effect
has been much discussed in various meteorological literature over the years.
In this area (Berkshire) we had some notable events in the late 1970's, and
the effect was always confined to built-up areas and the leeward of same. On
at least one occasion at Bracknell, the effect was marked enough to produce
solar halo phenomena as the ice crystals precipitated out. On another
occasion, I was driving towards Bracknell in the evening, and vertical
refraction pillars could be seen above all lampposts and car headlights over
a small area just to the west of the town, where the untreated pavements had
close to a cm of pptn deposits on them, and those a km or so to the west had
none. If I recall correctly, the air temp was about -2C. There were several
occasions when the effect was present in Bracknell, but not at Wokingham. It
seems likely that the contaminants are generated by a practice fairly common
in urban areas such as the burning of gas or oil in domestic appliances. I
have never seen the effect in a purely rural setting, except where this
abuts onto, and is down wind of, an urban area.

--
Bernard Burton
Wokingham, Berkshire, UK.

Satellite images at:
www.woksat.info/wwp.html

Bernard Burton wrote:


"Rob Brooks" wrote in message
...
Or do we call it snow? A covering of ice needles here in Farsley near
Leeds
Temperature down to -4C already at 6pm in mist/fog. Surprisingly the same
event occured on 19 February here in Leeds and Wakefield areas when
measureable depths were reported.


This effect is due to the freezing of supercooled fog droplets due to the
presence of 'ice nuclei' contaminants in the lower atmosphere. The effect
has been much discussed in various meteorological literature over the
years. In this area (Berkshire) we had some notable events in the late
1970's, and the effect was always confined to built-up areas and the
leeward of same. On at least one occasion at Bracknell, the effect was
marked enough to produce
solar halo phenomena as the ice crystals precipitated out. On another
occasion, I was driving towards Bracknell in the evening, and vertical
refraction pillars could be seen above all lampposts and car headlights
over a small area just to the west of the town, where the untreated
pavements had close to a cm of pptn deposits on them, and those a km or so
to the west had
none. If I recall correctly, the air temp was about -2C. There were
several occasions when the effect was present in Bracknell, but not at
Wokingham. It seems likely that the contaminants are generated by a
practice fairly common in urban areas such as the burning of gas or oil in
domestic appliances. I have never seen the effect in a purely rural
setting, except where this abuts onto, and is down wind of, an urban area.


I remember the halo phenomena in Bracknell in the late 70s or early 80s. I
believe that was an ice fog rather than a fall of ice needles. I recall
seeing ice fogs when I was a child - I'd be watching the fog passing by the
window when, all of a sudden, the water droplets would switch to solid
particles of ice. These particles were not needle-shaped and did not fall
to the ground - they floated.

My one memory of ice needles is the one I've described before that occurred
in December 1962. This happened over a wide area. I saw it start in Bedford
with quite large flakes of needles falling from a thick fog and the blue
sky simultaneously appearing overhead. A couple of hours later, at RAF
Wyton, I saw the pavements there decorated with the same type of flakes and
roughly the same concentration. It was a long time ago but I don't recall
that Wyton abutted on to much of an urban area.


--
Graham P Davis, Bracknell, Berks., UK. E-mail: newsman not newsboy