On Thursday, 5 March 2015 12:50:01 UTC, Metman2012 wrote:
On 05/03/2015 10:44, Eskimo Will wrote:

"Graham Easterling" wrote in message
...
On Thursday, March 5, 2015 at 9:18:39 AM UTC, Graham Easterling wrote:
On Thursday, March 5, 2015 at 8:04:22 AM UTC,
wrote:
"Dave Cornwell" wrote in message
...
On 04/03/2015 21:57, Dawlish wrote:
On Wednesday, March 4, 2015 at 7:54:27 PM UTC, Nick Gardner wrote:
On 04/03/2015 19:38, wrote:
I've marked this as 'OT' but obviously the weather is very
relevant!
I've only just found out this is happening at all and it's
going to be
a major event. No totality across the UK of course that passes
to the
north of Scotland but here it looks like being around 90%.
IIRC Aug
1999 was something like 94% so the events will be comparable.

No not comparable, there is a massive difference in terms of output
of heat
and light between 90 and 94%.


Indeed, and 99% is totally different to 100%. In 1999 it was a very
memorable effect as total darkness raced across the sea, plunging
from just dim to virtually dark in a second. I had an ex member of
USW camping in my garden at the time.

Some lucky people on the Lizard actually got a break in the cloud at
the right time.

Here's a picture I took of the 1996 partial eclipse.
http://penzanceweather.atspace.com/wpage7.html

I was living in Crowthorne at the time which was 95% and was hardly
noticed by people not looking out for it. But I had driven to Butser
Hill which was 98% and that was noticeable with a rather strange eerie
light at totality and of course a good view of the sun. I do regret not
heading SW given the forecast of cloud, to have experienced total
darkness would have been awesome. Still a memorable occasion. 90% will
not be noticeable at all it terms of light diminution unless you are
very sensitive.

Will
I was in Bracknell at the time and the light at maximum cover had a very
strange quality to it. I took a couple of photos but you would have to
be told that it was at 95%, though it's impossible with an auto camera
to show the light quality. My notes say 98% - where can we find out
where the percentage coverage was in in Bracknell/Crowthorne?

I do have a photo of the sun at maximum coverage.

The magnitude (i.e proportion of the sun's diameter covered) in Bracknell was 0.970 and the proportion of the sun's area covered 0.969. The two figures are rarely the same, the area proportion being less than than the diameter proportion except near totality when the moon is "large".
I strongly disagree with Will's assertion that an obscuration of 90% is barely detectable. I have seen an eclipse (25 Feb 1971) where the obscuration was only 58% yet the sun, in a clear sky, looked just a little weak and slightly "wrong". I'd say less than 50% is probably undetectable without instruments. This is, of course, because of the eye's enormous dynamic range. Full sun compared to full moon is at least half a million (19 camera stops) but you can still read a newspaper.

Tudor Hughes, Warlingham, Surrey.