[SQM] a "ground albedo influence" night

Audrey Fischer audrey at starpals.org
Sun Dec 20 16:39:48 UTC 2009

Thanks Jan
This is very useful.

Also do you know whether there was even the slightest mention of light  
pollution issues during the entire Copenhagen Climate Change summit,   
interviews, or media?

On Dec 20, 2009, at 10:16 AM, Jan Hollan wrote:

> Dear friends,
> just a reminder: a bright night with almost all landscape covered with
> cold white snow (here in Brno, just very concentrated salt water could
> thaw it recently) is an ideal opportunity to get the important number:
>            what amount of sky luminance is due
>          to the light disperesed from the ground
> This differs within towns and far from them, of course. But even  
> within
> towns, the amount of sky luminance due to direct emissions from
> luminaires is, fwith no snow, larger, unless the lighting is fully
> shielded.
> Comparison of snowless and snow-rich winter measurements (with the  
> same
> zenith extinction, if possible, or under a known one at least) is  
> our main
> tool in this respect. It can overweight any (wrong) models offered by
> polluters.
> Fabio and I have written about it several times already, but there  
> are not
> many data like that yet. We had a week with snow here in Brno  
> already, but
> this night is the first clear-sky one.
> So, don't miss the opportunity, if it will appear -- tonight or any  
> other
> night this winter.
> best,
>  jenik
> PS. sorry for not responding to darksky issues at all, I'm  
> overwhelmed by
> working on the climate enlightment these months.
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