It's those moist westerlies when the forecast is (as todays MetO
forecast see chart http://www.metoffice.gov.uk/weather/...t_weather.html)
cloudy on exposed west facing coasts, sunny spells in shelter.

In fact out at Sennen, where I've just spent the morning, it's sunny
on the beach. The low cloud forms as the air rises up the cliff, so a
mile inland it's quite dull. This is so often the case. The moors are
misty In Penzance its low base small cumulus & sunny spells. A quick
look at XCWeather reveals Scilly is reporting no cloud (or it was at
11:00BST).

Currently (12:30) around 17C in Penzance, so still quite warm.

Graham
Penzance

Graham

Still sunny here too but becoming very hazy.

Interesting to note that despite yesterday's (and the last month's) blue
sky, the sun index has struggled to make it much above 4 down here in the
South West. And yet, today (despite the milkiness/haze of the sky) the sun
index has gone above 6.

What was it in the previous air mass that filtered out much of the UV, even
when the sky was deep blue.

I would expect at this time of year we would be getting a sun index of 6 or
higher during clear conditions. Now we're back into a westerly regime, this
seems to be the case.

Currently at 14:55, 18.9C, RH 48%, DP 7.6C, 1017.2 mb (S), Wind 12 mph WNW,
Gusting 22 mph.
________________
Nick G
Otter Valley, Devon
83 m amsl
http://www.ottervalley.co.uk

Still sunny here too but becoming very hazy.

Interesting to note that despite yesterday's (and the last month's) blue
sky, the sun index has struggled to make it much above 4 down here in the
South West. And yet, today (despite the milkiness/haze of the sky) the sun
index has gone above 6.

What was it in the previous air mass that filtered out much of the UV, even
when the sky was deep blue.


Nick

Just checked Camborne (where it's very hazy indeed, bright rather than
sunny a lot of the time) and it's 6.

I think it's partly the change of air mass, but also I've noticed
(mainly from practical experience!) that thin layers of low cloud, or
patchy sea mist which let the sun through, seem to enhance the UV
intensity. (Can anyone confirm this?).

Graham
Penzance

Graham Easterling wrote:
Still sunny here too but becoming very hazy.

Interesting to note that despite yesterday's (and the last month's) blue
sky, the sun index has struggled to make it much above 4 down here in the
South West. And yet, today (despite the milkiness/haze of the sky) the sun
index has gone above 6.

What was it in the previous air mass that filtered out much of the UV, even
when the sky was deep blue.


Nick

Just checked Camborne (where it's very hazy indeed, bright rather than
sunny a lot of the time) and it's 6.

I think it's partly the change of air mass, but also I've noticed
(mainly from practical experience!) that thin layers of low cloud, or
patchy sea mist which let the sun through, seem to enhance the UV
intensity. (Can anyone confirm this?).

Graham
Penzance




So far today mainly cloudy but index has reached 5.8,(although fallen
back to 3.0 now) yet in the three days of wall to wall sunshine(1st-3rd
of May) we did not achieve 5.0
An explanation would be very interesting.

Alan
Wincanton
www.wincantonweather.org.uk

"Graham Easterling" wrote in message
s.com...


Just checked Camborne (where it's very hazy indeed, bright rather than
sunny a lot of the time) and it's 6.

I think it's partly the change of air mass, but also I've noticed
(mainly from practical experience!) that thin layers of low cloud, or
patchy sea mist which let the sun through, seem to enhance the UV
intensity. (Can anyone confirm this?).

I did hear once that thin cloud can cause a kind of 'lensing'
effect wherby UV rays are effectively magnified.
However this seems rather fanciful to be honest so I don't
really know what the answer is.
--
Col

Bolton, Lancashire
160m asl