[Darksky]Re: about the pictures (fwd)

Jan Hollan
Fri, 12 Apr 2002 21:14:06 +0200 (CEST)

> Dear folks, we have no claim what-so-ever to the copyrights. We would just
> like to honour the photographer he helped us in a tough spot in really
> hasty timetable by paying from the trouble: we donīt think of actually
> buying anything to be "owned". We are just happy if you use the same or
> what-ever pictures for any purposes that are dear to us ALL, particularly
> of course to fight against light pollution.

Dear Marko, 

 that sounds very fine (Rudolf has been pleased by the possibility to get
some money, it does not happen him so often...), thank you. I have just
sent the info to Bob, as he has asked me to find some images.

> I think I havenīt really understood what EXACTLY is going on in you land
> regarding THE LIGHTS themselves. I understand both from our assistent
> editorīs interview as well as from Ron Baalkeīs Nasa news mails that
> lights directed ABOVE the horizon are now forbidden. What am I missing
> here? The talk about specific lamp types above seem quite hebrew.
> The news mail did let assume that the light pollution above Brno HAS
> ALREADY IMMENSELY IMPROVED or something like that. Is this true? How is it
> possible? Did already one entire city actually drop its level of outdoor
> lighting. That would be a dream.
> Marko

The regulations will demand explicitly no direct light over
horizon for replacements and new installations. They should, as the
definition of LP within the law stresses the light over horizon. So, they
are not forbidden yet but will be, soon. I hope even without
grandfathering -- to achieve this, a precedent that such exceptions have
not been used elsewhere, even if allowed by the laws, would be
encouraging, or, on the contrary, an information, where they have been
used exactly (I'll ask DSLF and OLF on this).

The lamp spreading now in Brno is of this type (only from the Italian
pages I've found that the lamp is named Victor). What is better, is less
glare than before in the streets concerned, this is what I have mentioned
as a positive example. And of course less sky pollution, as each per cent
of light just above horizon increases the sky luminance caused by the lit
terrain some 30 per cent (probably more over a non-flat terrain, like
downtown), as a rule-of-thumb.

Unfortunately, the bulbs are far too strong, their ballast has a label as
being suitable just for 150W HPS or MH bulbs, as I saw today after opening
the fixture (I'll add images of inside of the lamp next week). The
illumination is probably higher on those streets than before. 100W or
perhaps even 50W bulbs would be adequate. I'll insist on the utility that
even downtown the lamps are to be dimmed after 22 h and even more after 24
h (I guess they do not dim them just due to a superstition that more light
= less crime, I'll publish the Czech translation of Barry Clark's lp40
tonight to cure it). Some road lighting IS DIMMED in Brno already (to 50
per cent power, so perhaps 30 per cent light, there is no problem to do
that with 150W HPS according to the Brno people installing such
technology), these folks have to be supported to dim all outdoor lighting
(such a demand should be in the implementing regulations following our new
law as well).

The people from the Brno lighting utility say they have reduced the
lighting levels in most of the city already. I'm not sure if this is true
(they have definitely achieved less power and considerable savings, but
with new, more efficient lamps, it's not so clear concerning light), we'll
try to check it using the archived photometry data (and getting sky
luminances from them).

clear skies,