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Bertwhistle
28 January 2017 16:45:41

The UK has for a long time been described has having a maximum UV index of 8, at one location in Cornwall, rarely. This was challenged at the MetO in recent years until they adjusted their forecast UV range from 1-7 to 1-8. A factor of 8 is now more commonly forecast eg on the BBC website in June & July.


This interesting link gives a UV reading in Reading in June 2000 (this was, admittedly, a notable dry air high UV event) of about 9.6. Reading is some distance inland away from the S coast where higher UV indices are often recorded.There are other events I am sure if anyone has the time to scroll through the site.


On that June day I was walking north in the Wallop Brook valley and had my shirt off for about 15 minutes before my wife told me to put it back on. I have a white skin that tans easily. I burned. I just thought the UV index was a worthwhile topic- some of us look out for it cranking up to 2 in March each year with some excitement!


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


 


Bertie, Itchen Valley.
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Bertwhistle
28 January 2017 16:52:16

Forgot to add- notice on some days the curve is constant, but these are not the days with the highest UV- the spikier days, suggesting cumulus or other interruptions, reach the highest values; cloud cover or air type intensifying the UV?


Bertie, Itchen Valley.
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Bolty
28 January 2017 18:19:20
Good website that. It gives a good visualisation of UV indices in the UK. It's a website I might use more often.

I wonder if these very high UV indices can be attributed to decreased ozone in the stratosphere. If you get an area of atmosphere with a lower concentration of stratospheric ozone over a region near the summer solstice (or at any time of year, in fact), it is bound to result in a higher index.
Scott
Blackrod, Lancashire (4 miles south of Chorley) at 156m asl.
My weather station 
Whether Idle
28 January 2017 18:29:27


some of us look out for it cranking up to 2 in March each year with some excitement!


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


 


Originally Posted by: Bertwhistle 


As the proud owner of my own little green power station - my 15 panel  solar array - I notice how the solar output ticks up markedly under any sun at the very start of March, compared to a week or two beforehand.  Exciting times, I relish this time of year, the best of the astronomical winter just about to come, and the promise of increasing daylength and some sparkling sunshine just around the corner. 


Dover, 5m asl. Half a mile from the south coast.
Gusty
28 January 2017 20:41:00

Good website that. 


March 7th is the day when the sun starts to turn my skin a healthier looking colour. Tanning opportunity continues until about 2nd October down here for me. By mid January I start to look decidedly pale !


Between 7-14th March the sun really does ramp up.


Not long now...


Steve - Folkestone, Kent
Current conditions from my Davis Vantage Vue
https://www.wunderground.com/dashboard/pws/IFOLKE11 
Join Kent Weather on Facebook.
https://www.facebook.com/stevewall69/ 



Bertwhistle
28 January 2017 20:47:44


Good website that. 


March 7th is the day when the sun starts to turn my skin a healthier looking colour. Tanning opportunity continues until about 2nd October down here for me. By mid January I start to look decidedly pale !


Between 7-14th March the sun really does ramp up.


Not long now...


Originally Posted by: Gusty 


I agree- at least, in our sort of latitude; I do remember a slight bronzing (you'd have to want to see it, if you know what I mean) out on Purbeck in Feb 87, under long periods of sun, but my earliest gentle tanning recently was first week of March, re-roofing the shed. The shadow of the house down the lawn shortens quickly through March too.


Bertie, Itchen Valley.
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Bertwhistle
18 February 2017 08:09:13

http://www.bbc.co.uk/weather/2633858


First UV2 forecast for the Itchen Valley today. That'll open the crocuses.


Just seen yesterday's data- it did just reach 2 at around 1200 but sadly I was locked away in a dark box.


Bertie, Itchen Valley.
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Bertwhistle
20 February 2017 08:41:01

UV max at Reading 1.7 on Saturday and 1.6 yesterday despite the cloud.


Bertie, Itchen Valley.
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Bertwhistle
21 February 2017 07:43:28

Reading max UV 2.1 yesterday; highest of the year so far.


Bertie, Itchen Valley.
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Bertwhistle
22 February 2017 09:09:40

UV 1.6 max at Reading yesterday.


Bertie, Itchen Valley.
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Bertwhistle
23 February 2017 09:30:02

Reading UV yesterday 1.4 max.


Bertie, Itchen Valley.
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warrenb
23 February 2017 11:25:54
I notice this also because of my PV panels. The last few days the peak output has been rising, and today was reaching 2.8kwh for a time.
Not long until I get the battery system installed with another 1.5 kw on garage roof, and will be electrically self sufficient for 9 months of the year.
Bertwhistle
24 February 2017 10:09:25

Reading UV max 1.8 yesterday. Already 1.3 at 9am this morning.


Bertie, Itchen Valley.
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some faraway beach
24 February 2017 10:42:16

Above 2 is the threshold I look for, because it's only above that number that exposure to UV enables the body to start generating vitamin D.


 


2 miles west of Taunton, 32 m asl, where "milder air moving in from the west" becomes SNOWMAGEDDON.
Well, two or three times a decade it does, anyway.
Bertwhistle
24 February 2017 15:24:52

Peaked at 1.9 today. Thought it could have passed two easily.


Bertie, Itchen Valley.
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warrenb
24 February 2017 15:27:01
Got a peak of 1.6 on my PWS. It is creeping up.
Retron
24 February 2017 17:31:17
It's certainly creeping up... another three weeks or so and it'll be a case of having to slop on loads of oily goop when I go on wolf walks. Roll on October!
Leysdown, north Kent
idj20
24 February 2017 17:34:26

A few extra minutes of solar heating in my famed west-facing hobby room this afternoon.  That's a few less minutes saved on the central heating. Of course, that only applies when the sun is actually out, like it has been off and on today.


Folkestone Harbour. 
Bertwhistle
25 February 2017 15:00:07

Only managed 1.3 today under extensive cloud- but that in itself is interesting, as Boxing Day was a beautiful sunny morning and it only reached 1.3 in the sunshine- so UV levels under the cloud now match those in bright sunshine near the solstice.


Bertie, Itchen Valley.
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Bertwhistle
26 February 2017 19:45:54

Reached 1.8 at 11a.m. before the weather turned for the day. Another week and we'll be seeing 2.5, I'm sure. Interesting that the Beeb/ MetO seem to be quite frequently forecasting 2s for the south earlier in the year than usual.


Bertie, Itchen Valley.
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Bertwhistle
27 February 2017 17:51:09

1.4 today.


Bertie, Itchen Valley.
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Lumi-Ukko
27 February 2017 20:23:26
Hope you don't mind me hijacking this thread as it is an interesting read! It prompted me look at my own UV indices here in Santa Monica:

http://www.homefacts.com/uvindex/California/Los-Angeles-County/Santa-Monica.html 

The highest it goes in December is 4, average in the 2's. In June and July it gets as high as 12, with averages in the 11's.

Today is currently 2.87 under think cloud. Should be a little over 5 later in the week under clear skies. By mid-March, it can already be as high as 8!

Interestingly, my skin has gotten used to it and I don't burn anywhere near as fast as I used to, and this is coming from a fair-skinned Yorkshireman.
Bertwhistle
27 February 2017 21:34:48

Hope you don't mind me hijacking this thread as it is an interesting read! It prompted me look at my own UV indices here in Santa Monica:

http://www.homefacts.com/uvindex/California/Los-Angeles-County/Santa-Monica.html

The highest it goes in December is 4, average in the 2's. In June and July it gets as high as 12, with averages in the 11's.

Today is currently 2.87 under think cloud. Should be a little over 5 later in the week under clear skies. By mid-March, it can already be as high as 8!

Interestingly, my skin has gotten used to it and I don't burn anywhere near as fast as I used to, and this is coming from a fair-skinned Yorkshireman.

Originally Posted by: Lumi-Ukko 


Glad you could join the thread Lumi!


It will be interesting to compare the Santa Monica/ various UK locations as the year progresses. I'd like to draw your attention to the day in June 2000 when phenomenally dry air gave a level in Reading of > 9. Some UK spots may have approached 10 that day. The previous forecast range of 1-7 for the UK (which, after my contestations with the metO was upped to 😎 were clearly related to general data, rather than extreme. I bet Santa M gets a 14 on the most extreme!


8 is a regular June/ July forecast in S. UK now. 6 from May to August is common. 


Bertie, Itchen Valley.
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Rob K
28 February 2017 10:46:21


Forgot to add- notice on some days the curve is constant, but these are not the days with the highest UV- the spikier days, suggesting cumulus or other interruptions, reach the highest values; cloud cover or air type intensifying the UV?


Originally Posted by: Bertwhistle 


Generally days with lower upper air humidity (like today!) are the days with deep blue skies and puffy cumulus clouds, so the UV reading between clouds will be higher.


Hazy summer days with higher humidity and a bit of general high cirrus tend to have fewer cumulus clouds.


 


This is a good link showing current and forecast upper air humidity. Dark browns (low humidity) are usually associated with deep blue skies (assuming there is no lower level cloud obscuring it of course!) 


http://www.instantweathermaps.com/GFS-php/showmap-euroupper.php?run=2017022806&var=RH&lev=300mb&hour=000


 


Yateley, NE Hampshire, 73m asl
"But who wants to be foretold the weather? It is bad enough when it comes, without our having the misery of knowing about it beforehand." — Jerome K. Jerome
Bertwhistle
28 February 2017 18:59:44

1.7 today.


Bertie, Itchen Valley.
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