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Nice work on putting more color into the table, do this remove the need for a 'Media Color' column in the table? I say scrap it. IanMcGreene 19:20, July 21, 2005 (UTC)
The article states that ratings beyond 11 are unlikely to occur. Not so - it is frequently 12 or 13 in Brisbane, where I live. In fact for a long time I wondered what the point of the scale was since the forecast here is always "extreme".
This site http://sedac.ciesin.org/ozone/maps/uvimap.shtml shows a range of values up to 21!
The article UV index is reiterating what we all know from generic, weather-report statements about the topic. I searched this article wanting to find out how long a person can stay unprotected in sun. For example, which duration of exposure at UV index of 4 (the minimal index that can burn skin, I gather) will result in a burn for pale skin? Then, if the same pale person were instead exposed to UV index of 5, how much less time could the person be in unprotected sunlight. Is it a linear or a log function? i.e. does UV index of 5 burn twice as fast as UV index of 4, or does it burn at a rate that is 1.25 (5/4) times faster?
My own understanding is that a pale person burns in about 20 min of summer sun -- what uv index might that be based upon? Inclusion of answers to these questions would bring the article a step beyond its current rather generic content.
I have heard that tanning can function like an SPF (sun protection factor) of 3. Does that mean it is equivalent to subtracting 3 from the UV index. In other words, how can one sensibly combine the net effects of sunscreen factors with UV index numbers? We keep hearing these numbers -- UV index and SPF -- all the time in summer, but no information source seems to be able to make much sense of them?
Who says so? And what do they mean by this? Will two days at level 4 equal one day at level 8? -- Uncle Ed 15:47, 5 December 2006 (UTC)
I came here looking for detailed facts. Is it a log scale or linear. How do permitted exposure and index relate (double time for each unit of index for example?). And the weighting (it has a name as do units of exposure I think). -- Memestream 16:28, 20 August 2007 (UTC)
OK I've got to the bottom of this now, and added a definition section to the article. -- Memestream 17:43, 20 August 2007 (UTC)
The following is a copy of the query and answer at my talk -- Memestream ( talk) 15:42, 14 April 2008 (UTC)
The UV index seems to mostly be used to attempt to scare/manipulate people to be afraid of sunlight. Real data is hard to find -- almost all of the information available to the public is predictions, not current or recent measurements. Usually, just one predicted number is given for the entire day. This prediction actually only applies to the time period around local solar noon, but information is often not given about the "safer" times before and after.- 96.237.69.64 ( talk) 18:12, 12 June 2010 (UTC)
UV Index and its modification by clouds and altitude
"As mentioned in section 2 the UV irradiance at any given place is affected by clouds and depends on the altitude above sea level. If, at a certain altitude, UVI0 represents the UV index for a cloud-free sky the following equation may be used to calculate the UV index, UVI , for a cloudy sky and at a different altitude:
UVI = UVI0 x CMF x (1+ 0.08 x dH)
where CMF is a so-called Cloud Modification Factor (a number between 0 and 1 – see Table 1) and ?H is the difference in altitude (in km) from the reference altitude of UVI0 . Table 1 shows CMFs for different cloud types and different cloud cover."
www.lamma.rete.toscana.it/uvweb/uvbooklet/par_4.htm - 96.237.69.64 ( talk) 02:54, 26 June 2010 (UTC)
Here you can see what amount of UV-rays hits the different parts of an human body. There are plenty of pictures for the 4 seasons, different time of the day, different position of the body towards the sun, different elevation over see level, standing, sitting and lying body.
http://edoc.ub.uni-muenchen.de/6023/1/Erianto_Christian.pdf in German, but enjoy the plenty pictures. Translate if necessary with Google language tools.
-- SonnePur ( talk) 09:31, 18 July 2011 (UTC)
Something in English Diurnal Variations in Solar Ultraviolet Radiation on Horizontal and Vertical Plane -- SonnePur ( talk) 09:51, 18 July 2011 (UTC)
![]() | This page is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
![]() | This page is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Nice work on putting more color into the table, do this remove the need for a 'Media Color' column in the table? I say scrap it. IanMcGreene 19:20, July 21, 2005 (UTC)
The article states that ratings beyond 11 are unlikely to occur. Not so - it is frequently 12 or 13 in Brisbane, where I live. In fact for a long time I wondered what the point of the scale was since the forecast here is always "extreme".
This site http://sedac.ciesin.org/ozone/maps/uvimap.shtml shows a range of values up to 21!
The article UV index is reiterating what we all know from generic, weather-report statements about the topic. I searched this article wanting to find out how long a person can stay unprotected in sun. For example, which duration of exposure at UV index of 4 (the minimal index that can burn skin, I gather) will result in a burn for pale skin? Then, if the same pale person were instead exposed to UV index of 5, how much less time could the person be in unprotected sunlight. Is it a linear or a log function? i.e. does UV index of 5 burn twice as fast as UV index of 4, or does it burn at a rate that is 1.25 (5/4) times faster?
My own understanding is that a pale person burns in about 20 min of summer sun -- what uv index might that be based upon? Inclusion of answers to these questions would bring the article a step beyond its current rather generic content.
I have heard that tanning can function like an SPF (sun protection factor) of 3. Does that mean it is equivalent to subtracting 3 from the UV index. In other words, how can one sensibly combine the net effects of sunscreen factors with UV index numbers? We keep hearing these numbers -- UV index and SPF -- all the time in summer, but no information source seems to be able to make much sense of them?
Who says so? And what do they mean by this? Will two days at level 4 equal one day at level 8? -- Uncle Ed 15:47, 5 December 2006 (UTC)
I came here looking for detailed facts. Is it a log scale or linear. How do permitted exposure and index relate (double time for each unit of index for example?). And the weighting (it has a name as do units of exposure I think). -- Memestream 16:28, 20 August 2007 (UTC)
OK I've got to the bottom of this now, and added a definition section to the article. -- Memestream 17:43, 20 August 2007 (UTC)
The following is a copy of the query and answer at my talk -- Memestream ( talk) 15:42, 14 April 2008 (UTC)
The UV index seems to mostly be used to attempt to scare/manipulate people to be afraid of sunlight. Real data is hard to find -- almost all of the information available to the public is predictions, not current or recent measurements. Usually, just one predicted number is given for the entire day. This prediction actually only applies to the time period around local solar noon, but information is often not given about the "safer" times before and after.- 96.237.69.64 ( talk) 18:12, 12 June 2010 (UTC)
UV Index and its modification by clouds and altitude
"As mentioned in section 2 the UV irradiance at any given place is affected by clouds and depends on the altitude above sea level. If, at a certain altitude, UVI0 represents the UV index for a cloud-free sky the following equation may be used to calculate the UV index, UVI , for a cloudy sky and at a different altitude:
UVI = UVI0 x CMF x (1+ 0.08 x dH)
where CMF is a so-called Cloud Modification Factor (a number between 0 and 1 – see Table 1) and ?H is the difference in altitude (in km) from the reference altitude of UVI0 . Table 1 shows CMFs for different cloud types and different cloud cover."
www.lamma.rete.toscana.it/uvweb/uvbooklet/par_4.htm - 96.237.69.64 ( talk) 02:54, 26 June 2010 (UTC)
Here you can see what amount of UV-rays hits the different parts of an human body. There are plenty of pictures for the 4 seasons, different time of the day, different position of the body towards the sun, different elevation over see level, standing, sitting and lying body.
http://edoc.ub.uni-muenchen.de/6023/1/Erianto_Christian.pdf in German, but enjoy the plenty pictures. Translate if necessary with Google language tools.
-- SonnePur ( talk) 09:31, 18 July 2011 (UTC)
Something in English Diurnal Variations in Solar Ultraviolet Radiation on Horizontal and Vertical Plane -- SonnePur ( talk) 09:51, 18 July 2011 (UTC)
![]() | This page is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |