No subject


Wed Feb 13 13:13:33 UTC 2008


now and the length of time the most recent snow cover has existed and the t=
emperature variations the cover has experienced (melting, refreezing meltin=
g...)=A0 Photometric measurements using simple instruments and conducted by=
 interested persons could be used to generalize snow cover reflectivity.=A0=
 The measurements would be made from several points in the illuminated area=
.=A0 One essential point would be directly beneath the source.=A0 Other poi=
nts would be along a straight line away from the first point.=A0 Remember, =
the intensity of the illumination falls of rapidly even from fully shielded=
 sources.
=A0
Joe Mayer
=A0
--- On Sun, 12/20/09, Audrey Fischer <audrey at StarPals.org> wrote:


From: Audrey Fischer <audrey at StarPals.org>
Subject: [walnutpointobservatory] Re: [SQM] a "ground albedo influence" nig=
ht
To: "Jan Hollan" <jhollan at amper.ped.muni.cz>
Cc: ida at amper.ped.muni.cz, magnitude6 at yahoogroups.com, OutdoorLighting-Foru=
m at yahoogroups.com, sqm at unihedron.com, DarkSkyCommunities at yahoogroups.com, w=
alnutpointobservatory at yahoogroups.com, ida at darksky.org, "CAS E-Mail" <casre=
sponse at gmail.com>, "Volobog DNR" <DNR.Volobog at Illinois.gov>
Date: Sunday, December 20, 2009, 10:39 AM


Thanks Jan
This is very useful.

Also do you know whether there was even the slightest mention of light=A0=
=20
pollution issues during the entire Copenhagen Climate Change summit,=A0=A0=
=A0
interviews, or media?
:>)
Audrey

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:
>
>=A0 =A0 =A0 =A0 =A0 =A0 what amount of sky luminance is due
>=A0 =A0 =A0 =A0 =A0 to the light disperesed from the ground
>
> This differs within towns and far from them, of course. But even=A0=20
> 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=A0=20
> same
> zenith extinction, if possible, or under a known one at least) is=A0=20
> 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=A0=20
> are not
> many data like that yet. We had a week with snow here in Brno=A0=20
> already, but
> this night is the first clear-sky one.
>
> So, don't miss the opportunity, if it will appear -- tonight or any=A0=20
> other
> night this winter.
>
> best,
>=A0 jenik
>
> PS. sorry for not responding to darksky issues at all, I'm=A0=20
> overwhelmed by
> working on the climate enlightment these months.
>
>
>
> _______________________________________________
> sqm mailing list
> sqm at unihedron.com
> http://unihedron.com/cgi-bin/mailman/listinfo/sqm
>



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--0-1928714097-1261366252=:58370
Content-Type: text/html; charset=iso-8859-1
Content-Transfer-Encoding: quoted-printable

<table cellspacing=3D"0" cellpadding=3D"0" border=3D"0" ><tr><td valign=3D"=
top" style=3D"font: inherit;"><DIV id=3Dyiv1764208742>
<DIV>Jan Hollan !!</DIV>
<DIV>&nbsp;</DIV>
<DIV>Hi, Jan.&nbsp; I'm Joe Mayer, the observatory director of the Chicago =
Astronomical Society and I've investigated this problem with an illuminatio=
n engineer from Portland, Oregon.&nbsp; I can't put my hands on the papers =
right now; nor can I remember the engineer's name.&nbsp; However, he is a f=
ormer board member of the IDA.</DIV>
<DIV>&nbsp;</DIV>
<DIV>His calculations&nbsp;and measurements&nbsp;produced the following res=
ults:&nbsp; Given a fully shielded illumination source such as a street lig=
ht, from a dry&nbsp;asphalt surface, 8% of the incident light is reflected =
into the atmosphere.&nbsp; From a dry concrete surface 25% of the incident =
light is reflected into the atmosphere.&nbsp; From a wet surface it's no pr=
oblem:&nbsp; It's raining.</DIV>
<DIV>From a snow covered surface the reflectivity is a function of the type=
 of snow and the length of time the most recent snow cover has existed and =
the temperature variations the cover has experienced (melting, refreezing m=
elting...)&nbsp; Photometric measurements using simple instruments and cond=
ucted by interested persons could be used to generalize snow cover reflecti=
vity.&nbsp; The measurements would be made from several points in the illum=
inated area.&nbsp; One essential point would be directly beneath the source=
.&nbsp; Other points would be along a straight line away from the first poi=
nt.&nbsp; Remember, the intensity of the illumination falls of rapidly even=
 from fully shielded sources.</DIV>
<DIV>&nbsp;</DIV>
<DIV>Joe Mayer</DIV>
<DIV>&nbsp;</DIV>
<DIV>--- On <B>Sun, 12/20/09, Audrey Fischer <I>&lt;audrey at StarPals.org&gt;=
</I></B> wrote:<BR></DIV>
<BLOCKQUOTE style=3D"BORDER-LEFT: rgb(16,16,255) 2px solid; PADDING-LEFT: 5=
px; MARGIN-LEFT: 5px"><BR>From: Audrey Fischer &lt;audrey at StarPals.org&gt;<=
BR>Subject: [walnutpointobservatory] Re: [SQM] a "ground albedo influence" =
night<BR>To: "Jan Hollan" &lt;jhollan at amper.ped.muni.cz&gt;<BR>Cc: ida at ampe=
r.ped.muni.cz, magnitude6 at yahoogroups.com, OutdoorLighting-Forum at yahoogroup=
s.com, sqm at unihedron.com, DarkSkyCommunities at yahoogroups.com, walnutpointob=
servatory at yahoogroups.com, ida at darksky.org, "CAS E-Mail" &lt;casresponse at gm=
ail.com&gt;, "Volobog DNR" &lt;DNR.Volobog at Illinois.gov&gt;<BR>Date: Sunday=
, December 20, 2009, 10:39 AM<BR><BR>
<DIV class=3DplainMail>Thanks Jan<BR>This is very useful.<BR><BR>Also do yo=
u know whether there was even the slightest mention of light&nbsp; <BR>poll=
ution issues during the entire Copenhagen Climate Change summit,&nbsp;&nbsp=
;&nbsp;<BR>interviews, or media?<BR>:&gt;)<BR>Audrey<BR><BR>On Dec 20, 2009=
, at 10:16 AM, Jan Hollan wrote:<BR><BR>&gt; Dear friends,<BR>&gt;<BR>&gt; =
just a reminder: a bright night with almost all landscape covered with<BR>&=
gt; cold white snow (here in Brno, just very concentrated salt water could<=
BR>&gt; thaw it recently) is an ideal opportunity to get the important numb=
er:<BR>&gt;<BR>&gt;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; what amount of=
 sky luminance is due<BR>&gt;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; to the ligh=
t disperesed from the ground<BR>&gt;<BR>&gt; This differs within towns and =
far from them, of course. But even&nbsp; <BR>&gt; within<BR>&gt; towns, the=
 amount of sky luminance due to direct emissions from<BR>&gt;
 luminaires is, fwith no snow, larger, unless the lighting is fully<BR>&gt;=
 shielded.<BR>&gt;<BR>&gt; Comparison of snowless and snow-rich winter meas=
urements (with the&nbsp; <BR>&gt; same<BR>&gt; zenith extinction, if possib=
le, or under a known one at least) is&nbsp; <BR>&gt; our main<BR>&gt; tool =
in this respect. It can overweight any (wrong) models offered by<BR>&gt; po=
lluters.<BR>&gt;<BR>&gt; Fabio and I have written about it several times al=
ready, but there&nbsp; <BR>&gt; are not<BR>&gt; many data like that yet. We=
 had a week with snow here in Brno&nbsp; <BR>&gt; already, but<BR>&gt; this=
 night is the first clear-sky one.<BR>&gt;<BR>&gt; So, don't miss the oppor=
tunity, if it will appear -- tonight or any&nbsp; <BR>&gt; other<BR>&gt; ni=
ght this winter.<BR>&gt;<BR>&gt; best,<BR>&gt;&nbsp; jenik<BR>&gt;<BR>&gt; =
PS. sorry for not responding to darksky issues at all, I'm&nbsp; <BR>&gt; o=
verwhelmed by<BR>&gt; working on the climate enlightment these
 months.<BR>&gt;<BR>&gt;<BR>&gt;<BR>&gt; __________________________________=
_____________<BR>&gt; sqm mailing list<BR>&gt; <A href=3D"http://us.mc814.m=
ail.yahoo.com/mc/compose?to=3Dsqm at unihedron.com" rel=3Dnofollow target=3D_b=
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mailman/listinfo/sqm" rel=3Dnofollow target=3D_blank>http://unihedron.com/c=
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