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[DSLF] Digest Number 1552

There are 6 messages in this issue.

Topics in this digest:

      1. 050114 Re: Skyglow models
           From: "Christopher J Baddiley" <cj.baddiley@physics...>
      2. 050114 re   Re:   Re: ground reflectance and uplight
           From: "Christopher J Baddiley" <cj.baddiley@physics...>
      3. Re:  Re: Greenhouses and Bob Gent
           From: Mike and Dianne Best <mrbdb@bellsouth...>
      4. Re: ground reflectance and uplight
           From: Steve Davis <w2sgd@juno...>
      5. Re: Re: ground reflectance and uplight
           From: Darren Baskill <dbl@star....ac.uk>
      6. Re: Re: Audubon
           From: BGSTARLITE@aol...


Message: 1         
   Date: Fri, 14 Jan 2005 03:07:20 -0000
   From: "Christopher J Baddiley" <cj.baddiley@physics...>
Subject: 050114 Re: Skyglow models

Dear David,

In trying to answer your many qusetions.... 

I do not believe my model to be 100% accurate, far from it, but it is a guide.

My draft paper is only for a general audience, and does not address your questions. It does not include detailed equations. The PowerPoint one does include the essential equations but does not link them. I have not written a scientific paper with a very detailed description. I simply do not have time. All my effort went into writing the programs. I also tried to do some uncalibrated photometry of night sky images, this is the only data I have available. I do not have any resources, time or funding. I am prepared to give the PowerPoint presentation and general description to any one interested.

The atmospheric model does include extinction and scattering componerts in combination as given in a referenced paper.

Ground reflection is at about the 10% level for any scattered path. So I would expect a 10% infill for reflected light that has been scattered downwards. I am not modelling to such accuracies, when  different light designs have so much larger an effect. but I am still developing the model when time allows. and I hope to include this.  

The basic simplification was to allow direct light for luminaries not to be blocked, .. to be generally clear of most buildings over a 360 degree azimuth extent. clearly not true in detail, but suffices as an approximation.

Low angle extrene reflections are blocked by obstacles in general. The angle can be varied or removed and results compared. This represents suburban areas around towns seen from  a distance from elevated locations, as seen in many photographs of towns in the UK.  I am not in a position to do detailed local topologies, I am only interested in general principles here.

I would like to include multiple scattering, but with my limited computing power I cannot consider it.  I consulted a scattering expert about this, and was informed that the approximation is reasonable, true even for thin clouds. My program took 90 minutes to run on our Pentium II, 5 minutes on a Pentium Centrino. I hate to think of the overhead for mutliple scatter.

The model is not for poor visibility conditions. I am only modelling conditions of potentially starlit skies. The conditions of medium to poor visibility are not ones where any potential astronomer or star gazer would use.
Spectral content is dealt with the in the model, spectral curves are stored in the data sets. I preset the wavelengths of interest, and so can compare one wavelength against another. I have plotted curves for two wavelengths. The atmospheric particle content ratios and height distributions are defined according to a referenced paper. The Rayleigh scattering has wavelength dependence as do the reflectivity's of reflecting surfaces.

Concrete reflections are very significant in town centres where roads are enclosed by buildings.  But here the light is blocked from low angle view by the buildings. I do not model town centres, it is a separate problem. All the pictures in our library of towns show huge suburban sprawl of lights, town centres are rarely seen. Two surfaces are modelled.. the road and its surrounds, scattering from both is included. Reflections off the primary and secondary surfaces are calculated for all angles.

There is skyglow from FCOs, the scatter  peaks at about 1/3 the distance from the source to viewer distance in the cases that I have modelled. The FCO figures are substantially lower than other types. some 10 to 5 times lower than tilted SOX and 2 times lower than shallow bowls that I have looked at. This is for distant location views, some 15 Km or more form the source.

Trees are quite a problem to model, with so many scattering surfaces. I have limited my model to asphalt and grass for now. I also looked at snow for comparison.

Concrete does reflect more away from the normal in common with other suffaces. I would be interested in seeing any real figures for this. I have not use any concrete surfaces. The material is not commonly found in suburban or rural areas in the UK. It is common in town centres, but I have not modelled those as I have said.
To build a model that does all these things would be a huge undertaking, but not impossible given enough time and effort. A whole town could be modelled given the effort.

I am only looking of general principles for now.

I note that the skyglow angular and scatter component distributions I get are not so different from the curves shown by Garstang and all those I have seen to refer to his work. Not seen any on the work of Chris Lughinbuhl.

I did not use the Garstang equation set because I wrote my model independently, before reading any of those papers. But his approach to model the source is very empriicle. Mine is based on actual luminaire data, and is for idividual luminaires for comparisons, that is the difference.

Hope this helps.


----- Original Message ----- 
From: "David Keith" <david.keith@mindspring...>
> I think this could be the best way to address my questions and would
> appreciate an electronic copy - for my own use only - sent to
> david.keith@mindspring...


Message: 2         
   Date: Fri, 14 Jan 2005 08:43:38 -0000
   From: "Christopher J Baddiley" <cj.baddiley@physics...>
Subject: 050114 re   Re:   Re: ground reflectance and uplight

Dear Carlo,

Not sure what a dingbat is but I will take it as a compliment, as I rarely
get them.
My wife say that I am nearly useless, so really anything is better than

You are absolutely right. We need to persuade governments and councils
designers etc.

That is why I have not spent  my efforts writing scientific papers....

that is why I wrote my model ! and.....

That is why for 15 years I have spent nearly all by spare time preparing and
giving public talks (not just light pollution) and why I have been working
for the Campaign for Dark Skies all that time.

That is why we had a big input into the previous government's lighting in
the Countryside publication.

That is why I wrote a report and we gave a presentation and evidence to the
Parliamentary science and Technology Committee investigating light pollution
over year ago, and that persuaded the Government to act.

That is why we also put input to try DEFRA's Living Places public
discussion, now  leading to the Clean Neighbourhoods and Environment Bill
that hopes to outlaw gross light intrusion. Parliamentary reading soon this

That is why I was on the discussion committee at the Office of Deputy Prime
Minister on the draft for the Annex to PPS23,  that will require all
Councils to have external lighting policies to minimise light pollution in
new schemes,  as clauses in planning approval requirements.

That is why was on the British Standards committee for Road Lighting, 10
years ago, and got in this statement amongst others... 'In all open areas
Full cutoff lighting should be used' (since been modified I believe somewhat
into classes).

That is why I have given presentation on sky glow measurements and my model
results at three European Dark sky meetings, and also my presentation was
read for me by a sympathetic senior lighting engineer at the Barcelona
conference of lighting engineers.

That is why I gave a presentation to senior executives of the Institute of
Lighting engineers last year showing the results of my model that shows FCOs
offer huge reductions in sky glow and so that is where my first publication
will be.. the ILE journal.

And that is why the ILE will produce a full colour booklet for members and
councils based on this work.

I have just been asked to talk to the ILE Western region meeting in May, and
they changed the date of the meeting so I could speak to them.

That is why we collaborated what the Campaign to Protect Rural England in
their Night blight Campaign.
CfDS is working on all these issues.

That is why I spent the whole holidays preparing a presentation for the CPRE
Night blight conference next week. concentrating on Environmental issues,
including likely catastrophic global effects, also presenting  model results

The UK government has woken up and realised the problem, hence PPS23 and
Clean Environment Bills. But it is only a first step.

 The Highways agency is also aware and uses FCOs almost entirely.

The problem is mostly with cash strapped Councils who go for the cheapest ,
often just changing the bulb for brighter one  alas !. Also housing estate

The government offers funding for replacement lighting schemes, mostly in
cities, but the councils often do  not go for least sky glow, but  increased
uniformity and brightness. etc.

I am in discussion currently with view to cost effective solution
consultancy (or more) in this area, i.e. energy saving and long term running
cost savings, looking for business opportunities for the company that
employs me for my more normal line of work.

 Hope this helps


----- Original Message ----- 
From: "Carlo Godel" <regiaero@acsol...>

>  If you dingbats want to study this to death go ahead but it will not
> solve or ameliorate anything don't give an inch we have been brainwashed
> by the power companies for so long that it is going to take some real
> push to get anything at all.


Message: 3         
   Date: Fri, 14 Jan 2005 05:57:13 -0500
   From: Mike and Dianne Best <mrbdb@bellsouth...>
Subject: Re:  Re: Greenhouses and Bob Gent

On 1/13/05 12:18 AM, "ctstarwchr" <ctstarwchr@aol...> wrote:

>   If 5% of the light reflected up from the wet road lit
> with full cutoff fixtures it would be surprising to me
Tell that to David Keith.

Mike Best


Message: 4         
   Date: Fri, 14 Jan 2005 10:18:39 -0500
   From: Steve Davis <w2sgd@juno...>
Subject: Re: ground reflectance and uplight

Carlo wrote:
> ... save substantial amounts of money by shielding
> lights and putting in lower wattage fixtures as
> the old ones burn out

Why wait (which could take 20-30 years)?  That is like having
another study.  Replace them now.  Now only will you save money,
reduce the glare and trespass problems which don't have direct
dollar values assigned to them.

It didn't take much study to put the original lights in.
A "little" hindsight should help.

Like I told an EPA official the other night regarding noise
and light, people want the problem solved NOW! - not some excuse
such as "it meets the agency's design guideline numbers".

Trying telling your boss or employer (outside of civil service
or government work) you need more time "to study the problem."
You will have plenty of time looking for a new job.

-sd, another unwilling victim looking for others to speak up

PS:  If Einstein though compound interest was a powerful force,
think of what compound frustration could do.


Message: 5         
   Date: Fri, 14 Jan 2005 13:24:08 +0000 (GMT)
   From: Darren Baskill <dbl@star....ac.uk>
Subject: Re: Re: ground reflectance and uplight

>  If you dingbats want to study this to death go ahead but it will not
> solve or ameliorate anything don't give an inch we have been brainwashed
> by the power companies for so long that it is going to take some real

Dear Carlo,

  I am very thankful to those that do study this to death!

  One of the usual brush off from councils is "You aren't a lighting
engineer.  You know nothing.  Go away."  (In so many words!)

  If someone does study this to death, on my behalf, I can say "True - but
these people [waving a paper in their face] DO know more than you and say
that you are wrong!  So sort it out!"

>    Steve is right, no up light at all, every damn light indoors is

Steve is right - but every time I say that to the council they said "Well,
FCO's are good enough because...".  Other people's studies help me prove
they are good enough.  So the disscussion between Chris & David is very
useful and I encourage it!

> be heard and when someone wants to study lighting tell them we've lived
> with it for far too long it's time to do something and quit talking
> about it.

  But then they say "Ah - but your neighbour DOES want their house lit up
all night for [in]security reasons..." (this latter one still grates
me so much...!)

> Some of you sound like government workers who want to make
> another study so more money can be spent. Enough of that BS spend some

They/I want another study to prove that EVERY POSSIBLE EXCUSE for not
having good lighting is totally wrong!

> energy on getting the lighting down to reasonable levels show them how
> you can allow them to save substantial amounts of money by shielding
> lights and putting in lower wattage fixtures as the old ones burn out.

This does not work as well in the UK, since our electricity is
cheaper than in the states, so I believe.  Ours is about 2p a kw h at
night - what's that?  About 4 cents/kW hr in american money??  Something
like that.  So the payback time is usually/irritatingly much longer.

> Do not take no for an answer, show government the already written
> studies that show excessive lighting is bad for everyone. Do it don't
> just talk about it.

  But people taking about it gives me a bigger stick with which to beat
the government with!

  Every example that is put on this discussion group makes the wad of
paper, with which I use to knock sense into people, heavier!




Message: 6         
   Date: Fri, 14 Jan 2005 22:53:32 EST
   From: BGSTARLITE@aol...
Subject: Re: Re: Audubon

I'm tired of reading all the goals of the Audubon Society and seeing a  
mention of light pollution once in a blue moon in a society publication,  then 
nothing. They don't address the issue enough. I have given plenty of talks  at 
different Audubon locations and many of their people, or should I say most of  
their people, don't seem to realize the impact of LP on the very subjects they  
would like to save on this Earth, flora and fauna.
Is it just that they would like to leave the fight in the hands of groups  
like IDA, NELPAG and others? Am I missing something? I certainly hope I am.  I 
hope I'm being unfair in this e-mail and just haven't educated myself on the  
Audubon Society's real stand on the subject. 

[Non-text portions of this message have been removed]


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