-> Dunno ...  but the introduction of the UV index wasn't well done;  
-> being told that tomorrow's sun will take 10 minutes to fry you  
-> gives you courses of action,  while a predicted UV Index of 11+  
-> for both today and tomorrow kind of numbs the brain into so-what-?  
-> land. 
  
Maybe the change is in reaction to diversification of your population. 
Some people's skin burns much more easily than others'. "Ten minutes" 
might be dangerously long for an untanned north-European, but totally 
safe for a dark-skinned descendant of people from the tropics. 
  
Some sort of objective scale is useful. The one we have seems to be 
adequate here in Canada, where UV levels never reach the "11+" extreme, 
but inadequate in New Zealand. Surely, it could and should be extended 
to higher numbers. If the index was 15 one day and 25 the next, people 
would get a good idea of what was going on. 
  
-> All very true;  our ozone hole is never mentioned without the  
-> words "biggest in the world" attached (preferably with an  
-> unexplained fuzzy photo of a soggy tangerine) - this might offer  
-> some real differences,  although my last visit to a website that  
-> published the latest UV statii put the nastiest spot over the west  
-> coast of South America. 
  
I think I've mentioned Punta Arenas, a city in the extreme south of 
Chile, where UV levels allegedly reach the highest levels in the world. 
However, the people there are mainly quite dark-skinned, so they can 
tolerate higher exposures than fair-skinned Kiwis. 
  
The effect due to the ellipticity of the Earth's orbit is real, but 
insufficient to explain the large difference in UV levels between NZ 
and Canada. The effect of the ellipticity would cause a variation of 
only about three percent. So I guess ozone depletion must be the main 
cause. 
  
                                 dow 
--- Platinum Xpress/Win/WINServer v3.0pr5