[SQM] a "ground albedo influence" night
jhollan at amper.ped.muni.cz
Sun Dec 20 16:16:57 UTC 2009
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
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
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.
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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