UV index 4 from 29 March

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cordyman
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Re: UV index 3 from ~14 March

Post by cordyman » Sun Mar 02, 2014 7:06 pm

Cheers Stephen. We need an infra red scale forcast then lol

Otorongo get on it :lol:

I want me some infra red 50 % forcasts :oops: :oops:


otorongo
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Re: UV index 3 from ~14 March

Post by otorongo » Sun Mar 02, 2014 7:24 pm

One site says that London can get index 4 in April, so I think we get index 3 considerably earlier than end of April. That site also gives us a max of index 6 in June, and I know we can get a 7.

Also this site forecasts index 3 for Brittany (not to be confused with Britain ;)) this Wednesday: http://www.uvawareness.com/uv-index/uv- ... ion=london , not far latitudinally from London. So it's not hard to imagine index 3 in London 10 days later.
Last edited by otorongo on Sun Mar 02, 2014 7:32 pm, edited 1 time in total.


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stephenprudence
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Re: UV index 3 from ~14 March

Post by stephenprudence » Sun Mar 02, 2014 7:28 pm

otorongo wrote:One site says that London can get index 4 in April, so I think we get index 3 considerably earlier than end of April. That site also gives us a max of index 6 in June, and I know we can get a 7.
Im sure after mid March the UV index increases exponentially, I mean we are capable of getting a 2 at this time of year, but it takes clear skies, and low air pollution. I think I have encountered a UV 4 at the end of April before.

Another idea is that the UV index is stronger from south to north, this is actually not true, the UV index is actually strongest from west to east, in the British Isles - why I have no idea, but it is for some reason in my time watching the UV output. I suspect it's mixture of the Atlantic ocean and less air pollution.
Last edited by stephenprudence on Sun Mar 02, 2014 7:31 pm, edited 1 time in total.
Heswall, Wirral, UK
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stephenprudence
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Re: UV index 3 from ~14 March

Post by stephenprudence » Sun Mar 02, 2014 7:29 pm

cordyman wrote:Cheers Stephen. We need an infra red scale forcast then lol

Otorongo get on it :lol:

I want me some infra red 50 % forcasts :oops: :oops:
clear skies does it. icon_cheers
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)


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cordyman
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Re: UV index 3 from ~14 March

Post by cordyman » Sun Mar 02, 2014 7:53 pm

stephenprudence wrote:
otorongo wrote:One site says that London can get index 4 in April, so I think we get index 3 considerably earlier than end of April. That site also gives us a max of index 6 in June, and I know we can get a 7.
Im sure after mid March the UV index increases exponentially, I mean we are capable of getting a 2 at this time of year, but it takes clear skies, and low air pollution. I think I have encountered a UV 4 at the end of April before.

Another idea is that the UV index is stronger from south to north, this is actually not true, the UV index is actually strongest from west to east, in the British Isles - why I have no idea, but it is for some reason in my time watching the UV output. I suspect it's mixture of the Atlantic ocean and less air pollution.
Is that why us westerners can have warm Springs, when those on the east complain its cold?


Axel
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Re: UV index 3 from ~14 March

Post by Axel » Sun Mar 02, 2014 9:37 pm

I was in Paris the last few days and the sun was notably stronger than in Amsterdam. Even when shining through the clouds you could feel the burn on your face, in Amsterdam the sun is weaker and the light is paler too, even on sunny days.

The sunshine in Paris seems more intense, lighting up the area with a more warm brighter light. Is this the differnce between 49 and 52 latitude?


Tom2006
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Re: UV index 3 from ~14 March

Post by Tom2006 » Sun Mar 02, 2014 11:11 pm

Makes all the difference Axel.
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otorongo
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Re: UV index 3 from ~14 March

Post by otorongo » Mon Mar 03, 2014 9:11 am

3 degs of latitude difference is roughly 8 days at this time of year: http://www.timeanddate.com/worldclock/a ... =-11&day=1

So in Amsterdam in 8 days the sun should be as good as it is now in Paris.

This only confirms the index 3 in London on the 14th :)


Axel
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Re: UV index 3 from ~14 March

Post by Axel » Mon Mar 03, 2014 9:50 am

Thanks very interesting. I see that the differnce in sun angles is minimal, but still i notice the light is different in france.
Could it be that the light in france in general is intenser than in Amsterdan due to more clear Atlantic air?


otorongo
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Re: UV index 3 from ~14 March

Post by otorongo » Mon Mar 03, 2014 9:56 am

Axel wrote:Thanks very interesting. I see that the differnce in sun angles is minimal, but still i notice the light is different in france.
Could it be that the light in france in general is intenser than in Amsterdan due to more clear Atlantic air?
I find that the sun in London is different, more yellow than the white light in the Med, even with the same angles.


Axel
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Re: UV index 3 from ~14 March

Post by Axel » Mon Mar 03, 2014 10:13 am

Exactly, that is what i meant. Sun angles are only part of it. There is something different. For example California is famous for it's light but florida isn't. Same angles, diffent atmosphere. It's not the proximity of the sea (although coastal locations have brighter light in general compared to inland locations, also in Holland). It probably has more to do with the dryness/clearness of the air.


Axel
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Re: UV index 3 from ~14 March

Post by Axel » Mon Mar 03, 2014 10:16 am

Perhaps the distribution of light in very dry air isn't hampered by tiny (water)particles as much?


Nathan
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Re: UV index 3 from ~14 March

Post by Nathan » Mon Mar 03, 2014 11:57 am

stephenprudence wrote:Another idea is that the UV index is stronger from south to north, this is actually not true, the UV index is actually strongest from west to east, in the British Isles - why I have no idea, but it is for some reason in my time watching the UV output. I suspect it's mixture of the Atlantic ocean and less air pollution.
Actually UV increases with latitude, the closer to the equator you are the higher the UV. In the UK there isn't a huge difference in latitude from the far north to the far south, so the main reasons for higher UV levels would be down to clearer conditions, which could occur anywhere within the UK. The highest UV levels are found on the south coast though as this area not only has the most southerly latitudes of the UK, but is also the area that receives more sunshine per annum & thus clearer skies... Altitude also increases UV levels, for every 1000 meters the UV increases by 10%, but not many people would live at such heights in the UK to see these increased levels... And haze from pollution can actually increase UV levels too...
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Nathan
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Re: UV index 3 from ~14 March

Post by Nathan » Mon Mar 03, 2014 12:06 pm

cordyman wrote: Is that why us westerners can have warm Springs, when those on the east complain its cold?
No, that would be dependant on wind direction. The north sea is at its coldest in early spring so an easterly wind makes the east coast cold, but this wind warms over land, so by the time it reaches the west coast it is warmer (in sunny weather especially)...
Malta - USDA Zone 11a


otorongo
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Re: UV index 3 from ~14 March

Post by otorongo » Mon Mar 03, 2014 12:08 pm

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).


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