UV index 4 from 29 March

GREVILLE
Posts: 2866
Joined: Sat Jan 22, 2011 10:39 am
Location: South London

Re: UV index 3 from ~14 March

Post by GREVILLE » Mon Mar 03, 2014 11:07 pm

So figures on a UV index can be boosted by conditions encouraging more reflected light. This must account for a comment heard by a BBC weather forecaster who said that sunlight can be even stronger with patchy fairweather cloud than gin-clear blue skies.


User avatar
stephenprudence
Posts: 9028
Joined: Fri Aug 01, 2008 8:40 pm
Location: Heswall, Wirral

Re: UV index 3 from ~14 March

Post by stephenprudence » Mon Mar 03, 2014 11:18 pm

GREVILLE wrote:So figures on a UV index can be boosted by conditions encouraging more reflected light. This must account for a comment heard by a BBC weather forecaster who said that sunlight can be even stronger with patchy fairweather cloud than gin-clear blue skies.
Where have you come across blue gin?? :lol:

Bombay Sapphire?

Yes certainly high cloud can magnify UV.. however it won't be taken on board by UV models.
Heswall, Wirral, UK
USDA equivalent average temperature zone: 9a/RHS zone 3
AHS Heat Zone: 1
Last 5 winter minimums:
2007: -0.1C, 2008: -4.2C, 2009: -5.7C, 2010: -10.5 (record), 2011: -4.9C, 2012: -5.3, 2013: -4.5C (so far)


User avatar
Yorkshire Kris
Posts: 10151
Joined: Wed Dec 16, 2009 8:59 am
Location: Rural South Wakefield, Yorkshire Lat 53.64 Long-1.54

Re: UV index 3 from ~14 March

Post by Yorkshire Kris » Tue Mar 04, 2014 8:46 am

All this talk of UV and no mention of skin cancer? Remember to keep convered up and apply sunscreen. It doesn't need to be hot and sunny for uv levels to be damaging to the skin.


otorongo
Posts: 1426
Joined: Tue Jan 10, 2012 5:12 pm
Location: sub-subtropical London

Re: UV index 3 from ~14 March

Post by otorongo » Tue Mar 04, 2014 9:10 am

Yorkshire Kris wrote:All this talk of UV and no mention of skin cancer? Remember to keep convered up and apply sunscreen. It doesn't need to be hot and sunny for uv levels to be damaging to the skin.
Yeah skin cancer in index 3... never leave the house without a tank...

Image

I don't use protection for indices 11 or below, it's not really necessary, and strong sun is needed for good health. Using sun protection defeats the point of being in the sun as it cuts off your skin from the beneficial UV light.


User avatar
Nathan
Posts: 4101
Joined: Sun Oct 12, 2008 4:51 pm
Location: St Paul's Bay, Malta

Re: UV index 3 from ~14 March

Post by Nathan » Tue Mar 04, 2014 10:53 am

otorongo wrote:
Nathan wrote:And haze from pollution can actually increase UV levels too...
Increase or decrease?

Coastal areas also have higher UV levels due to the light reflected by the water.

When you're out skiing in the Alps in the winter you can get sunburns, not only because of the altitude but also the sn*w reflecting more UV (and the sun is 5 deg higher down there).
Increase. This is taken from the WHO website:
UV intensities are highest under cloudless skies. Clouds generally reduce UV intensity, but light or thin clouds
have little effect and under certain conditions may even enhance the UV intensity. Hazy days generally have
higher amounts of water vapour; UV scatter in the atmosphere increases and can result in a higher personal UV
exposure. Thus, even though haze or cloud cover can cause one to feel cooler, the UV exposure can still be high.
http://www.who.int/uv/publications/proUVrad.pdf
Malta - USDA Zone 11a


User avatar
Nathan
Posts: 4101
Joined: Sun Oct 12, 2008 4:51 pm
Location: St Paul's Bay, Malta

Re: UV index 3 from ~14 March

Post by Nathan » Tue Mar 04, 2014 11:05 am

otorongo wrote:
Yorkshire Kris wrote:All this talk of UV and no mention of skin cancer? Remember to keep convered up and apply sunscreen. It doesn't need to be hot and sunny for uv levels to be damaging to the skin.
Yeah skin cancer in index 3... never leave the house without a tank...

[ Image ]

I don't use protection for indices 11 or below, it's not really necessary, and strong sun is needed for good health. Using sun protection defeats the point of being in the sun as it cuts off your skin from the beneficial UV light.
With respect the amount of UV one can take is dependent on the colour of your skin, most of us would be very badly burnt at much much lower levels than you indicate. A UV of between 3 to 6 is 'moderate' for light skinned people & fair skinned people can burn at lower levels than that. Even people with naturally brown or black skin have a medium to high risk of burning in UV levels of 7 to 10, let alone 11! :?

Slip, slap, slop people icon_thumright
Malta - USDA Zone 11a


otorongo
Posts: 1426
Joined: Tue Jan 10, 2012 5:12 pm
Location: sub-subtropical London

Re: UV index 3 from ~14 March

Post by otorongo » Tue Mar 04, 2014 11:57 am

Nathan wrote:
UV intensities are highest under cloudless skies. Clouds generally reduce UV intensity, but light or thin clouds
have little effect and under certain conditions may even enhance the UV intensity. Hazy days generally have
higher amounts of water vapour; UV scatter in the atmosphere increases and can result in a higher personal UV
exposure. Thus, even though haze or cloud cover can cause one to feel cooler, the UV exposure can still be high.
I think what this quote means to say is that in hazy conditions the UV is more diffused, so when you're in the shade you get more UV from the diffused light than you would on a clear day.

With clear skies the light is less diffused and more direct. As a result you get little UV in the shade, but full-on UV in the sun, assuming you're exposed to it properly - sitting at the optimal angle etc.

So as long as you are in the sun, clear is better than hazy. And you know where I will be... and how close to optimal my exposure will be :D

It is only those pale, photophobic people who spend all day indoors and squint at the sun when they come out of their boxes that will get more UV in hazy conditions, because they always seek shade and the haze will pump extra UV into the shade (at the cost of the sun-hungry people like myself).


User avatar
stephenprudence
Posts: 9028
Joined: Fri Aug 01, 2008 8:40 pm
Location: Heswall, Wirral

Re: UV index 3 from ~14 March

Post by stephenprudence » Tue Mar 04, 2014 2:30 pm

Ive never burnt below UV 7, but I have burnt pretty spectacularly in UV 10 .. when I was in Mediterranean. I'm part of Britain darker quartile too (as a native), but Ive known people to say they've been burnt in February before.
Heswall, Wirral, UK
USDA equivalent average temperature zone: 9a/RHS zone 3
AHS Heat Zone: 1
Last 5 winter minimums:
2007: -0.1C, 2008: -4.2C, 2009: -5.7C, 2010: -10.5 (record), 2011: -4.9C, 2012: -5.3, 2013: -4.5C (so far)


otorongo
Posts: 1426
Joined: Tue Jan 10, 2012 5:12 pm
Location: sub-subtropical London

Re: UV index 3 from ~14 March

Post by otorongo » Tue Mar 04, 2014 3:01 pm

I've been burnt in January (in Costa Rica and Mexico), November and December (in Rio) but never in February, as by February my skin is already dark enough.

Recent studies suggest the lack of sun causes more cancer (not just skin, but all kinds) than the excess of it. For example in Britain the further South you go the lower the percentage of cancer cases.

I find that the sun in London is already too hot for comfort, but a breeze can go a long way icon_sunny


User avatar
Exotic Life
Posts: 1818
Joined: Fri Feb 16, 2007 3:03 pm
Location: Southwest of the Netherlands

Re: UV index 3 from ~14 March

Post by Exotic Life » Tue Mar 04, 2014 3:11 pm

UV 3 possible here by the end of this week.


otorongo
Posts: 1426
Joined: Tue Jan 10, 2012 5:12 pm
Location: sub-subtropical London

Re: UV index 3 from ~14 March

Post by otorongo » Wed Mar 05, 2014 4:26 pm

Exotic Life wrote:UV 3 possible here by the end of this week.
Same here :)

Weekend and the following week looking sunny icon_sunny with index 3 every day excepting Monday.


User avatar
stephenprudence
Posts: 9028
Joined: Fri Aug 01, 2008 8:40 pm
Location: Heswall, Wirral

Re: UV index 3 from 8 March

Post by stephenprudence » Wed Mar 05, 2014 5:30 pm

UV 1 here is also were due this week.
Heswall, Wirral, UK
USDA equivalent average temperature zone: 9a/RHS zone 3
AHS Heat Zone: 1
Last 5 winter minimums:
2007: -0.1C, 2008: -4.2C, 2009: -5.7C, 2010: -10.5 (record), 2011: -4.9C, 2012: -5.3, 2013: -4.5C (so far)


GREVILLE
Posts: 2866
Joined: Sat Jan 22, 2011 10:39 am
Location: South London

Re: UV index 3 from 8 March

Post by GREVILLE » Wed Mar 05, 2014 8:11 pm

Probably enjoyed UV 2 to 3 today. Wonderful to do some gardening in a tee shirt. My face has a little glow as I post this.


User avatar
Nathan
Posts: 4101
Joined: Sun Oct 12, 2008 4:51 pm
Location: St Paul's Bay, Malta

Re: UV index 3 from 8 March

Post by Nathan » Thu Mar 06, 2014 9:16 am

A UV of 5 is forecast here next week icon_sunny
Malta - USDA Zone 11a


otorongo
Posts: 1426
Joined: Tue Jan 10, 2012 5:12 pm
Location: sub-subtropical London

Re: UV index 3 from 8 March

Post by otorongo » Thu Mar 06, 2014 9:18 am

Nathan wrote:A UV of 5 is forecast here next week icon_sunny
Good for you, that's already close to sufficient icon_sunny


Post Reply