Chalfont St Giles - Wednesday 5th November 2008
------------------------------------------------------------

0630z NNE F1 7000 HZ 8Sc012 09.3/07.7 1017


Norman.

--
Norman Lynagh
Chalfont St Giles, Buckinghamshire
85m a.s.l.
(remove "thisbit" twice to e-mail)

Chalfont St Giles - Wednesday 5th November 2008
------------------------------------------------------------

0630z NNE F1 7000 HZ 8Sc012 09.3/07.7 1017

0900z NNE F1-2 5000 HZ 6St005 8St008 09.9/08.8 1017

24-HR STATISTICS
Max (0900-0900z): 10.7 at 1515z
Min (0900-0900z): 9.0 at 0415z
Grass min (0900-0900z): 7.3
Rain (0900-0900z): Trace


Norman.
--
Norman Lynagh
Chalfont St Giles, Buckinghamshire
85m a.s.l.
(remove "thisbit" twice to e-mail)

Chalfont St Giles - Wednesday 5th November 2008
------------------------------------------------------------

0630z NNE F1 7000 HZ 8Sc012 09.3/07.7 1017

0900z NNE F1-2 5000 HZ 6St005 8St008 09.9/08.8 1017

24-HR STATISTICS
Max (0900-0900z): 10.7 at 1515z
Min (0900-0900z): 9.0 at 0415z
Grass min (0900-0900z): 7.3
Rain (0900-0900z): Trace

1500z NNE F1-2 10km 5St006 8St010 1016
RMK: It has been a dull grey day but I haven't noticed
any precipitation.


Norman.
--
Norman Lynagh
Chalfont St Giles, Buckinghamshire
85m a.s.l.
(remove "thisbit" twice to e-mail)

On Nov 5, 6:47*am, "Norman" normanthis...@thisbitweather-
consultancy.com wrote:
Chalfont St Giles *- *Wednesday 5th November 2008
------------------------------------------------------------

0630z * NNE *F1 * 7000 * HZ * 8Sc012 * 09.3/07.7 * 1017

Norman. * *

--
Norman Lynagh
Chalfont St Giles, Buckinghamshire
85m a.s.l.
(remove "thisbit" twice to e-mail)

Is that really haze, Norman? I know I've got a bit of thing
about "haze" and "hazy sunshine" but surely it's thin mist and not
solids in suspension.

Tudor Hughes, Warlingham, Surrey.

Tudor Hughes wrote:

On Nov 5, 6:47*am, "Norman" normanthis...@thisbitweather-
consultancy.com wrote:
Chalfont St Giles *- *Wednesday 5th November 2008
------------------------------------------------------------

0630z * NNE *F1 * 7000 * HZ * 8Sc012 * 09.3/07.7 * 1017

Norman. * *

--
Norman Lynagh
Chalfont St Giles, Buckinghamshire
85m a.s.l.
(remove "thisbit" twice to e-mail)

Is that really haze, Norman? I know I've got a bit of thing
about "haze" and "hazy sunshine" but surely it's thin mist and not
solids in suspension.

Tudor Hughes, Warlingham, Surrey.

I tend to agree with you Tudor but, by definition, it's only considered
to be mist if the relative humidity is 94 percent or more (or is it
more than 94 percent?). On this occasion the RH was only 90 percent so
whatever was obscuring the visibility couldn't be called mist. That
left haze as the only option. Or have the rules changed since I last
did "official" observations?

Norman
--
Norman Lynagh
Chalfont St Giles, Buckinghamshire
85m a.s.l.
(remove "thisbit" twice to e-mail)

"Norman" wrote in message
...
Tudor Hughes wrote:

On Nov 5, 6:47 am, "Norman" normanthis...@thisbitweather-
consultancy.com wrote:
Chalfont St Giles - Wednesday 5th November 2008
------------------------------------------------------------

0630z NNE F1 7000 HZ 8Sc012 09.3/07.7 1017

Norman.

--
Norman Lynagh
Chalfont St Giles, Buckinghamshire
85m a.s.l.
(remove "thisbit" twice to e-mail)

Is that really haze, Norman? I know I've got a bit of thing
about "haze" and "hazy sunshine" but surely it's thin mist and not
solids in suspension.

Tudor Hughes, Warlingham, Surrey.

I tend to agree with you Tudor but, by definition, it's only considered
to be mist if the relative humidity is 94 percent or more (or is it
more than 94 percent?). On this occasion the RH was only 90 percent so
whatever was obscuring the visibility couldn't be called mist. That
left haze as the only option. Or have the rules changed since I last
did "official" observations?

Norman
--
Norman Lynagh
Chalfont St Giles, Buckinghamshire
85m a.s.l.
(remove "thisbit" twice to e-mail)

AFAIK it is still mist if RH equal to or greater than 95%, haze if
visibility reduced by water droplets and RH 95%.

Will
--

"Norman" wrote ...

0630z NNE F1 7000 HZ 8Sc012 09.3/07.7 1017
[and]
Tudor Hughes wrote:

Is that really haze, Norman? I know I've got a bit of
thing
about "haze" and "hazy sunshine" but surely it's thin mist and not
solids in suspension.
[and]
"Norman" wrote ...
I tend to agree with you Tudor but, by definition, it's only
considered
to be mist if the relative humidity is 94 percent or more (or is it
more than 94 percent?). On this occasion the RH was only 90 percent
so
whatever was obscuring the visibility couldn't be called mist. That
left haze as the only option. Or have the rules changed since I
last
did "official" observations?
[and]
"Will Hand" wrote...
AFAIK it is still mist if RH equal to or greater than 95%, haze if
visibility reduced by water droplets and RH 95%.

.... that's certainly the "Observer's Handbook" guidance, but I seem to
remember that for practical purposes, we had a bit of latitude in
interpretation, but only by a few %. So U=90% and mist was *just*
about OK. The problem is ... does the screen environment accurately
match the 'open atmosphere' conditions?

Cause of many a 'happy' argument between shifts & also with the
station SSA :-)

Martin.


--
Martin Rowley
West Moors, East Dorset (UK): 17m (56ft) amsl
Lat: 50.82N Long: 01.88W
NGR: SU 082 023

"Martin Rowley" wrote in message
...
"Norman" wrote ...

0630z NNE F1 7000 HZ 8Sc012 09.3/07.7 1017
[and]
Tudor Hughes wrote:

Is that really haze, Norman? I know I've got a bit of thing
about "haze" and "hazy sunshine" but surely it's thin mist and not
solids in suspension.
[and]
"Norman" wrote ...
I tend to agree with you Tudor but, by definition, it's only considered
to be mist if the relative humidity is 94 percent or more (or is it
more than 94 percent?). On this occasion the RH was only 90 percent so
whatever was obscuring the visibility couldn't be called mist. That
left haze as the only option. Or have the rules changed since I last
did "official" observations?
[and]
"Will Hand" wrote...
AFAIK it is still mist if RH equal to or greater than 95%, haze if
visibility reduced by water droplets and RH 95%.

... that's certainly the "Observer's Handbook" guidance, but I seem to
remember that for practical purposes, we had a bit of latitude in
interpretation, but only by a few %. So U=90% and mist was *just* about
OK. The problem is ... does the screen environment accurately match the
'open atmosphere' conditions?

Cause of many a 'happy' argument between shifts & also with the station
SSA :-)

Martin.


My first posting was to RAF Finningley in Sept. 1970 (station 03360), now
closed. It was close to the industrial towns of Doncaster and Sheffield and
smoke haze was common. I remember one shift where the experienced observer
was reporting vibility below aviation fog limits but also smoke haze,
present weather code 04. Great arguments with the collecting centre at Manby
ensued saying that he should be reporting fog not smoke. But he was correct
as the RH was circa 94% and the air was full of dirty smoke, you could smell
it! He stuck to his guns. Doesn't happen much nowadays of course with
cleaner air generally. Good old days, cough, cough :-)

Will
--

Will Hand wrote:


"Martin Rowley" wrote in message
...
"Norman" wrote ...

0630z NNE F1 7000 HZ 8Sc012 09.3/07.7 1017
[and]
Tudor Hughes wrote:

Is that really haze, Norman? I know I've got a bit of thing
about "haze" and "hazy sunshine" but surely it's thin mist and not
solids in suspension.
[and]
"Norman" wrote ...
I tend to agree with you Tudor but, by definition, it's only considered
to be mist if the relative humidity is 94 percent or more (or is it
more than 94 percent?). On this occasion the RH was only 90 percent so
whatever was obscuring the visibility couldn't be called mist. That
left haze as the only option. Or have the rules changed since I last
did "official" observations?
[and]
"Will Hand" wrote...
AFAIK it is still mist if RH equal to or greater than 95%, haze if
visibility reduced by water droplets and RH 95%.

... that's certainly the "Observer's Handbook" guidance, but I seem to
remember that for practical purposes, we had a bit of latitude in
interpretation, but only by a few %. So U=90% and mist was *just* about
OK. The problem is ... does the screen environment accurately match the
'open atmosphere' conditions?

Cause of many a 'happy' argument between shifts & also with the station
SSA :-)

Martin.


My first posting was to RAF Finningley in Sept. 1970 (station 03360), now
closed. It was close to the industrial towns of Doncaster and Sheffield
and smoke haze was common. I remember one shift where the experienced
observer was reporting vibility below aviation fog limits but also smoke
haze, present weather code 04. Great arguments with the collecting centre
at Manby ensued saying that he should be reporting fog not smoke. But he
was correct as the RH was circa 94% and the air was full of dirty smoke,
you could smell it! He stuck to his guns. Doesn't happen much nowadays of
course with cleaner air generally. Good old days, cough, cough :-)


Even earlier than that and in different circumstances, I remember several
times in the 62-3 winter where we knew what we'd got was fog but the air
temperature and ice-bulb difference resulted in an RH below 95%. As far as
I recall, we still coded it as fog.

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