From the point of view of amateur astronomers it will not be the end of
the world if there is extensive medium or high cloud, provided it is not too
thick and the sun is visible, maybe only just. The disc of Venus will be
*very* apparent as a large dark blob, much darker than even the biggest darkest
sunspot. I watched the Transit of Mercury on 9/5/70 by telescopic projection
and was struck by how dark the disc of Mercury appeared. Venus will be much
larger (about 3% of the sun's diameter) though its outline may be fuzzier,
having an atmosphere.
The ideal conditions to view the transit would, in my opinion, be through
quite thick fog, thin enough to see the sun, thick enough to cut down its
glare. The contrast between Venus and the sun's light will be enormous.
It will be interesting to observe the ingress and egress but there seems
to me to be no point in watching the whole thing. The relative positions of
the earth, Sun and Venus are now predictable to such accuracy that no
measurements taken by amateur astronomers ( or even professionals) can be of
any use whatever, even though in the past such transits have been used to
verify the various theories of motion of Solar System bodies. Much better
methods are available today.
All we hope to avoid is a day of unbroken thick cloud, but there are 6
hours in which to get your piccy, and I shall be surprised (and disappointed)
if the sun doesn't show its face in that time.
I could have done without the screaming Health and Safety warning. In
a group such as this it should be taken as read. It seems to me to be a sign
of a society that is so risk-averse as to be on the point of losing its nerve.

Tudor Hughes, Warlingham, Surrey.

"TudorHgh" wrote in message
...
I could have done without the screaming Health and Safety
warning. In
a group such as this it should be taken as read. It seems to me to be
a sign
of a society that is so risk-averse as to be on the point of losing
its nerve.


.... that warning will stay as long as I am posting that thread. There
are people looking in on this newsgroup who do not realise the risks
etc.

Martin.

Forecast discussion: Venus transit 2004 Jun 08

WARNING: THIS IS *NOT* A NAKED-EYE EVENT! YOU NEED EITHER AN INDIRECT
VIEWING METHOD, OR APPROVED FILTERS - SUNGLASSES ARE *NOT* SAFE.

For more details see:-
http://www.transitofvenus2004.org.uk/
and more generally:-
http://www.britastro.org/main/

Unless otherwise noted below, the discussion is based on products
available via:-
http://www.wetterzentrale.de/topkarten/

Forecast discussion: 2004 transit of Venus
Verifying: 2004 June 08 up to ~midday


2004 May 26: D-13: GFS
Synoptic:
L ... slow-moving well to the west of Scotland/occluding, with
developing wave-depression well to the WSW of area 'Shannon'. L ...
Finland - N.Russia. H ... central Med/Italy. Ridge ... Norwegian Sea.
Frontal zone lying from N.France ax Belgium to West Germany. Troughs
swinging across west/NW British Isles - front/trough southern Norway.

Run-to-run evolution: a 'warning-shot' that emphasises just how the runs
can change at this lead time. There *are* some consistent points though:
the relatively high pressure Norwegian Sea, and the frontal/baroclinic
zone affecting southern England/North France/Low Countries etc. These
elements have persisted throughout. (Yesterdays 12Z similar, with low in
NE Atlantic deeper, and closer to Scotland.)

Inference: from the PPN fields, areas thick cloud (and rain) all
southern England, parts of Wales/Channel/Northern France/Belgium -
extending across Netherlands/ west & NW Germany & into the English
Midlands/East Anglia etc., but as the wave moves east, conditions
improve West Country & SE Wales. Remainder of British Isles, better
prospect of broken cloud, at least at some time during the event, though
there is going to be the problem of an overhang of high/medium cloud
some central areas - as discussed elsewhere though, not necessarily a
major problem. Troughs swinging across Ireland and later Scotland -
though these should not obliterate the entire event. Now have a
trough/(?trowal) feature crossing southern Norway for a time.


--
FAQ & Glossary for uk.sci.weather at:-
http://homepage.ntlworld.com/booty.weather/uswfaqfr.htm

It will be interesting
to observe the ingress and egress but there seems to me to be no
point in watching the whole thing.

Since no one has ever observed the ingress/egress for over 100 years and
no photos exist that show this phenomenon we only have the word of the
observers at the time who say that the atmosphere of Venus glowed as the
planet moved over the edge of the Sun's disk.

This is one part of the transit I am most looking forward to. To observe
this you will almost certainly need a telescope and appropriate solar
filter.

This will be one of the most photographed astronomical phenomenon ever I
would imagine. Since photography was in its infancy when the last
transit occurred no 'good' photos of a Venus transit exist.

Any form of thinnish cloud or breaks will be OK, but can we have
unbroken sunshine from 6am to midday please! I will also be
demonstrating the transit to local school children so I would like at
least one break in any cloud, that's not too much to ask for is it?!

WARNING: THIS IS *NOT* A NAKED-EYE EVENT! YOU NEED EITHER AN INDIRECT
VIEWING METHOD, OR APPROVED FILTERS - SUNGLASSES ARE *NOT* SAFE.

For more details see:-
http://www.transitofvenus2004.org.uk/
and more generally:-
http://www.britastro.org/main/

Unless otherwise noted below, the discussion is based on products
available via:-
http://www.wetterzentrale.de/topkarten/

Forecast discussion: 2004 transit of Venus
Verifying: 2004 June 08 up to ~midday


2004 May 27: D-12: GFS
Synoptic:
L ... just SW of Iceland, with various secondaries: one swinging towards
SW Ireland & another just off eastern Scotland, moving north. Frontal
zone leaving eastern Britain (slow to clear NE Scotland/North Isles),
moving towards Norway and Denmark, clearing Northern France & Belgium,
but affecting Netherlands/NW Germany much of time. Further frontal zone
into SW Ireland, Celtic Sea and SW Approaches by midday. Inter-frontal
ridge crossing Britain from west.

Run-to-run evolution: We've now displaced the high well to the north in
the Norwegian Sea - for most areas read by this ng, a cyclonic picture,
with inter-trough/front 'gaps' is the best summing-up. This is NOT as
disastrous as it might seem: the systems all 'move', so if this run were
the one to turn up trumps, most of B & I (and N.France) should have a
prospect of viewing at some time over the 6-odd hours.

Inference: Thick/overcast NE Scotland - NE France - Low Countries -
Rhineland - SW Norway at start, this clearing for many by midday 8th,
but on this picture, not Shetland etc., and also SW Norway, Netherlands
(until late), and much of Germany. Decent prospect for many to west of
this frontal cloud, until the next front/trough into the SW by midday.


--
FAQ & Glossary for uk.sci.weather at:-
http://homepage.ntlworld.com/booty.weather/uswfaqfr.htm

WARNING: THIS IS *NOT* A NAKED-EYE EVENT! TAKE APPROPRIATE PRECAUTIONS.

For more details see:-
http://www.transitofvenus2004.org.uk/
and more generally:-
http://www.britastro.org/main/

Unless otherwise noted below, the discussion is based on products
available via:-
http://www.wetterzentrale.de/topkarten/

Forecast discussion: 2004 transit of Venus
Verifying: 2004 June 08 up to ~midday

2004 May 28: D-11: GFS
Synoptic:
Low ... (occluded) well to the west of Ireland, moving slowly NE. Low
.... (deepening) S.Sweden, moving slowly NE. High ... near Brittany,
moving / extending NE. Frontal zone SE France - Germany - southern
Scandinavia, moving east. Further front across Ireland & SW Approaches
by midday 8th.

Run-to-run evolution: Still low pressure NE Atlantic (though
centre-of-gravity further south than heretofore), with discrete frontal
system entering SW British Isles by midday - consistent with last run in
broad terms. Preceding frontal link now much further east at start of
event, with 'hiccup' phase over southern Sweden (rather than
North Isles etc.... probably problems with phasing of short-wave
troughs, frontal-waves etc., distinctly unreliable detail). This allows
a transient ridge to cross much of BI, Northern France, and eventually
Belgium/Netherlands/South Norway.

Inference: Extensive cloud-cover SE Norway, S Sweden, Germany, east & SE
France, breaking from west or northwest - any post frontal lower cloud
elsewhere should break readily - probably scattered showers though in
cold air northern areas. Good prospects associated with transient (cold)
ridge - not unbroken sunshine for all - then upper/medium cloud across
Ireland, West Wales, far SW England and SW Scotland through morning -
after fair start. (If this scenario were to be maintained - quite
hopeful for many in this ng.)

--
FAQ & Glossary for uk.sci.weather at:-
http://homepage.ntlworld.com/booty.weather/uswfaqfr.htm

According to past experience, the GFS forecast for the 8th June is coming
into a phase where everythiing goes haywire and hardly anything is
recognizable. This should last until about 3rd June when things begin to
settle. After that, details start to appear on the charts which then give
us the information we've been waiting for.

Cheers, Keith.

Martin Rowley schrieb:

WARNING: THIS IS *NOT* A NAKED-EYE EVENT! TAKE APPROPRIATE PRECAUTIONS.

For more details see:-
http://www.transitofvenus2004.org.uk/
and more generally:-
http://www.britastro.org/main/

Unless otherwise noted below, the discussion is based on products
available via:-
http://www.wetterzentrale.de/topkarten/

Forecast discussion: 2004 transit of Venus
Verifying: 2004 June 08 up to ~midday

2004 May 28: D-11: GFS
Synoptic:
Low ... (occluded) well to the west of Ireland, moving slowly NE. Low
... (deepening) S.Sweden, moving slowly NE. High ... near Brittany,
moving / extending NE. Frontal zone SE France - Germany - southern
Scandinavia, moving east. Further front across Ireland & SW Approaches
by midday 8th.

Run-to-run evolution: Still low pressure NE Atlantic (though
centre-of-gravity further south than heretofore), with discrete frontal
system entering SW British Isles by midday - consistent with last run in
broad terms. Preceding frontal link now much further east at start of
event, with 'hiccup' phase over southern Sweden (rather than
North Isles etc.... probably problems with phasing of short-wave
troughs, frontal-waves etc., distinctly unreliable detail). This allows
a transient ridge to cross much of BI, Northern France, and eventually
Belgium/Netherlands/South Norway.

Inference: Extensive cloud-cover SE Norway, S Sweden, Germany, east & SE
France, breaking from west or northwest - any post frontal lower cloud
elsewhere should break readily - probably scattered showers though in
cold air northern areas. Good prospects associated with transient (cold)
ridge - not unbroken sunshine for all - then upper/medium cloud across
Ireland, West Wales, far SW England and SW Scotland through morning -
after fair start. (If this scenario were to be maintained - quite
hopeful for many in this ng.)

--
FAQ & Glossary for uk.sci.weather at:-
http://homepage.ntlworld.com/booty.weather/uswfaqfr.htm

WARNING: THIS IS *NOT* A NAKED-EYE EVENT! TAKE APPROPRIATE PRECAUTIONS.

For more details see:-
http://www.transitofvenus2004.org.uk/
and more generally:-
http://www.britastro.org/main/

Unless otherwise noted below, the discussion is based on products
available via:-
http://www.wetterzentrale.de/topkarten/

Forecast discussion: 2004 transit of Venus
Verifying: 2004 June 08 up to ~midday

2004 May 29: D-10: GFS
Synoptic:
Low ... occluded (slow-moving) NE Atlantic. Low ... (complex)
Scandinavia - N.Russia. Ridge ... Brittany/Biscay to 'mirror' ridge from
NW Norwegian Sea - moving gently eastwards. Frontal zone eastern
France - Low Countries - NW Germany - Sweden, moving east with further
frontal trough swinging NE across Ireland, Wales & the West of England.

Run-to-run evolution: strong similarities to run 24hr ago, with low in
NE Atlantic, relatively high-pressure 'interim' period between one
frontal link over continental Europe and another coming in from the
Atlantic. Timing differences, but best not to make too much of these at
this range. If we get another 48hr worth of similar indications, then
this will show a strengthening probability for this picture when we get
to the 8th ... we'll also start getting other models in the picture too.

Inference: Extensive cloud cover associated with mainland Europe frontal
link - slow to clear, but broken cloud (at least - areas small amounts)
into much of east/central Britain, SW Norway (though with showers about
in north) and NW France; post-frontal cloud may be slower to clear Low
Countries/NE France depending upon the character of the air mass.
Encroaching upper/medium cloud across Ireland, Wales, West of England
and West/SW Scotland through morning - areas low cloud following.
Troublesome cloud link indicated (again - though a different mechanism)
through Shetland.


--
FAQ & Glossary for uk.sci.weather at:-
http://homepage.ntlworld.com/booty.weather/uswfaqfr.htm

WARNING: THIS IS *NOT* A NAKED-EYE EVENT! TAKE APPROPRIATE PRECAUTIONS.

For more details see:-
http://www.transitofvenus2004.org.uk/
and more generally:-
http://www.britastro.org/main/

Unless otherwise noted below, the discussion is based on products
available via:-
http://www.wetterzentrale.de/topkarten/

Verifying: 2004 June 08 up to ~midday


2004 May 30: D-09: GFS
Synoptic:
Low ... Iceland to Faeroes, moving ENE. Low ... Iberia to Biscay. High
.... North Sea - Denmark - Poland. High ... NE Atlantic, building
NE'wards across northern Britain.

Run-to-run evolution: almost no consistency with previous two 24hr
periods! This emphasises the caution needed with these extended
forecasts.
We now have a broad belt of HP from the NE Atlantic across the British
Isles/North Sea and onto the North European Plain. This demonstrates
that the models are going to have problems with the period - the key I
suspect lies later *this* week: the spaghetti plots are quite 'together'
up to Friday (with upper ridge indicated NW Europe), but looks like a
dogs-breakfast by Monday - not unusual!

Inference: at 00Z Frontal link N.Britain to Western Ireland, warm front
SW Norway ... implies extensive cloud these NW maritimes areas - this
should thin/break up as pressure builds across it, though amounts SC may
remain high; in north some post-cold front clearance indicated North
Isles. Elsewhere, cloud cover dictated by the character of the air-mass:
much of continental Europe and much UK/Eire would do well with this
pattern, though temporary infill cloud can't be ruled out later in the
morning. Coastal locations perhaps experiencing mist/fog/low cloud. Some
indication of troughing western Britain/Ireland during day, so
convective build here might be troublesome. Overall though, optimistic
elements again ... IF this were to be right!


--
FAQ & Glossary for uk.sci.weather at:-
http://homepage.ntlworld.com/booty.weather/uswfaqfr.htm

"Waghorn" wrote in message
...
the spaghetti plots are quite 'together'
up to Friday (with upper ridge indicated NW Europe), but looks like a
dogs-breakfast by Monday - not unusual
Todays London ensemble seems remarkable for the overall warming trend
and lack of ppn after Tuesday
http://www.wetterzentrale.de/pics/MT8_London_ens.html
presumably due to the persistant ridging from the SW,


Hi David,

Have you seen the ensemble forecast for Manchester, very odd operational
run from 7-13th June with regards to the rainfall. Hinting at daytime
convection maybe ? If so, it's going for some very heavy showers. Anyway,
too far ahead to take it as gospel.

http://www.wetterzentrale.de/pics/MT...ester_ens.html

ATB, Joe