From the Telegraph today:

"Unusual levels of UV are also being recorded in the UK at the moment - with the strength of the UV in some spots being as high as that in Cyprus and Gibraltar."

http://www.telegraph.co.uk/news/2017...-temperatures/

Can anybody shed any light (ouch) on this ? It makes no sense to me.

On Sunday, 18 June 2017 22:43:02 UTC+1, wrote:
From the Telegraph today:

"Unusual levels of UV are also being recorded in the UK at the moment - with the strength of the UV in some spots being as high as that in Cyprus and Gibraltar."

http://www.telegraph.co.uk/news/2017...-temperatures/

Can anybody shed any light (ouch) on this ? It makes no sense to me.

It could make sense in that Britain could be under an area of low ozone concentration but I've no idea whether it actually is or not. UV levels depend on the altitude of the sun among other things so it could be just that. Maybe it's just a generic warning because it's sunny - stock footage so to speak.
I was not terribly amused to read that current temperatures are 10°C (50°F) above average. That sort of confusion is normally stamped out in school. I was much more amused to see the warm nights described as "pretty uncomfortably mild" by someone from the Met Office. How can something be "uncomfortably mild"? It's an oxymoron of the first order. I can imagine someone like Will using it to describe a tropical incursion in winter but we'd all know what he meant. But the average member of the public would be asking themselves "what on earth does that mean?"

Tudor Hughes

On 19/06/2017 04:31, Tudor Hughes wrote:
On Sunday, 18 June 2017 22:43:02 UTC+1, wrote:
From the Telegraph today:

"Unusual levels of UV are also being recorded in the UK at the moment - with the strength of the UV in some spots being as high as that in Cyprus and Gibraltar."

http://www.telegraph.co.uk/news/2017...-temperatures/

Can anybody shed any light (ouch) on this ? It makes no sense to me.

It could make sense in that Britain could be under an area of low ozone concentration but I've no idea whether it actually is or not. UV levels depend on the altitude of the sun among other things so it could be just that. Maybe it's just a generic warning because it's sunny - stock footage so to speak.

I think they mean that the air is fairly clean and the sun almost as
high in the sky as it ever gets coming up to solstice. UV index online at:

https://uk-air.defra.gov.uk/data/uv-...on=daily_plots

Forecast and actual at Uccle, RMI Belgium

http://ozone.meteo.be/meteo/view/en/...+at+Uccle.html

I was not terribly amused to read that current temperatures are 10°C (50°F) above average.

They say some funny things in an attempt to popularise the weather
reports. It is rather warm at night at the moment even in our very thick
walled cool house the heat ingress is starting to become an issue.

--
Regards,
Martin Brown

Thanks All
Is there any reason to suppose that TM air is more likely to be associated with lower levels of ozone in the stratosphere than any other air mass? Do high surface temperatures have any relevant effect at all ? I don't see why. Surely surface UV levels are simply a factor of solar altitude and cloud/haze? (Perhaps humidity plays a role ?)

On 19/06/17 15:07, wrote:
Thanks All Is there any reason to suppose that TM air is more likely
to be associated with lower levels of ozone in the stratosphere than
any other air mass? Do high surface temperatures have any relevant
effect at all ? I don't see why. Surely surface UV levels are
simply a factor of solar altitude and cloud/haze? (Perhaps humidity
plays a role ?)


Back in the early 90s, when we produced regression equations from model
output to produce ozone and uv fields, the parameters used included 30
and 150hPa temperatures as well as latitude and total thickness. I think
the upper-atmosphere data was used to make an educated guess at the
ozone levels. No idea what's done these days.

I remember hearing that it's not just the amount and thickness of cloud
but also the type. For instance, half-cover of cumulus might increase UV
rather than decrease it.

--
Graham P Davis, Bracknell, Berks. [Retd meteorologist/programmer]
Web-site: http://www.scarlet-jade.com/
Never approach a bull from the front, a horse from the rear,
or an idiot from any direction! [Irish proverb]

Graham P Davis wrote:

On 19/06/17 15:07, wrote:
Thanks All Is there any reason to suppose that TM air is more likely
to be associated with lower levels of ozone in the stratosphere than
any other air mass? Do high surface temperatures have any relevant
effect at all ? I don't see why. Surely surface UV levels are
simply a factor of solar altitude and cloud/haze? (Perhaps humidity
plays a role ?)


Back in the early 90s, when we produced regression equations from model
output to produce ozone and uv fields, the parameters used included 30 and
150hPa temperatures as well as latitude and total thickness. I think the
upper-atmosphere data was used to make an educated guess at the ozone levels.
No idea what's done these days.

I remember hearing that it's not just the amount and thickness of cloud but
also the type. For instance, half-cover of cumulus might increase UV rather
than decrease it.

Low stratus and coastal fog seems to increase UV levels. The other Graham
(Penzance) knows more about this than I do. Sufficient to say that my fair skin
burns more on cloudy days than on sunny days.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
http://peakdistrictweather.org
Twitter: @TideswellWeathr

On 18/06/2017 22:43, wrote:
From the Telegraph today:
"Unusual levels of UV are also being recorded in the UK at the moment - with the strength of the UV in some spots being as high as that in Cyprus and Gibraltar."
Can anybody shed any light (ouch) on this ? It makes no sense to me.

I recorded a UV of 7.7 for yesterday (18th) and 7.8 for the day before.

These are nothing out of the ordinary for mid to late June given the
current 'atmospheric' set up. In tropical maritime air at this time of
year I can record UV above 9.0. My record is 10.

Later Wednesday and Thursday might see the UV climb towards 9.0 or
above. My highest UV so far this year was on the 12th June with 8.4.

--
Nick G
Otter Valley, Devon
20 m amsl
http://www.ottervalleyweather.me.uk

On Monday, June 19, 2017 at 8:58:04 AM UTC+1, Nick Gardner wrote:
On 18/06/2017 22:43, wrote:
From the Telegraph today:
"Unusual levels of UV are also being recorded in the UK at the moment - with the strength of the UV in some spots being as high as that in Cyprus and Gibraltar."
Can anybody shed any light (ouch) on this ? It makes no sense to me.

I recorded a UV of 7.7 for yesterday (18th) and 7.8 for the day before.

These are nothing out of the ordinary for mid to late June given the
current 'atmospheric' set up. In tropical maritime air at this time of
year I can record UV above 9.0. My record is 10.

Later Wednesday and Thursday might see the UV climb towards 9.0 or
above. My highest UV so far this year was on the 12th June with 8.4.

--
Nick G
Otter Valley, Devon
20 m amsl
http://www.ottervalleyweather.me.uk

9.7 at St Martin's Scilly today. The highest this year, but certainly not a record. Camborne has exceeded 10 in a warm sector SWesterly, and the highest I've seen at St Martins was 10.8 again in a humid SW with plenty of sea fog around. The current situation isn't quite right for record breaking.

Now 26C warmest day for 3 years - my Penzance record 29.7C. In this most maritime of places, the temperature struggles to get 10C over the offshore SST, which is currently around 16C or so. Some much warmer 'pools' close in e.g 20.2C at the Looe buoy. The SST in the SW approaches is way above normal for mid June. http://polar.ncep.noaa.gov/sst/rtg_l...maly_oper0.png

22C in the Jubilee Pool yesterday - positively tepid. A record 1,200 people went into the pool over the weekend. To think, if it wasn't for the 'Friend's' it would now be filled in for a car park. https://www.facebook.com/jubileepool/

Graham
Penzance -

On Sunday, June 18, 2017 at 10:43:02 PM UTC+1, wrote:
From the Telegraph today:

"Unusual levels of UV are also being recorded in the UK at the moment - with the strength of the UV in some spots being as high as that in Cyprus and Gibraltar."

http://www.telegraph.co.uk/news/2017...-temperatures/

Can anybody shed any light (ouch) on this ? It makes no sense to me.


From DEFRA

https://uk-air.defra.gov.uk/data/uv-index-graphs

Yesterday Belfast and Chilton (Oxfordshire) recorded unusually high UV Index values of 8.8 and 8.9 respectively.

Dick Lovett

On 19/06/2017 13:59, wrote:
From DEFRA
https://uk-air.defra.gov.uk/data/uv-index-graphs
Yesterday Belfast and Chilton (Oxfordshire) recorded unusually high UV Index values of 8.8 and 8.9 respectively.

I would imagine that 8.8 for Belfast is very unusual, especially
considering that the UV in Camborne, Cornwall was less at 8.4.

Interesting that UV was varying so much given that in Manchester it was
6.9 (still high for there).

Over the years of having an interest in UV levels, normally the South
West has the highest with a gradient across the SW Peninsula of UV
increasing the further west you go. Scilly nearly always has the highest
UV with places like Dorset or Somerset having the lowest (but still
higher than the rest of the UK).

The Met Office UV forecasts used to be useless and were just given as
being high if the sky is clear. In my experience the UV levels drop
after a cold front moves though even if the sky clears to unbroken
sunshine. Maritime polar/Arctic air will generally give the lowest UV
despite often having the clearest, deepest blue sky. The clarity of the
sky is no indicator to the level of UV.

I was told that the high UV in low pressure Maritime Tropical air was
due to ozone depletion above the warm sector. I do not know the
mechanisms as to why this happens.

Fair weather cumulus cloud can add around 1.0 but the highest occurs
when misty, low cloud weather breaks up a little to allow some sunshine
during tropical maritime air masses in the warm sector of a low
pressure. In June, July or early August this will give a UV above 9.0
even if the sky is slightly misty or hazy. If the sky remains cloudy the
UV can still reach 7+ and because the UV is coming from all parts of the
sky (as opposed to point source in a clear sky), people can get caught
out quite easily.

--
Nick Gardner
Otter Valley, Devon
20 m amsl
http://www.ottervalleyweather.me.uk