Author Topic: Light pollution GIF 1950-2010  (Read 515 times)

Alex Miller

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Light pollution GIF 1950-2010
« on: December 26, 2017, 06:55:43 PM »
Following is a small animated GIF I made.  It is a shame however.  I'd have LOVED to have seen the sky at our 'Dark Sky website' back at the 50's.

http://tinyurl.com/bvxtmn6



Paul Syring

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Re: Light pollution GIF 1950-2010
« Reply #1 on: December 27, 2017, 10:17:28 PM »
Hi GrafikDihzahyn.Great animation! Can I post it on our website?Thanks, Tom

revenade

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Re: Light pollution GIF 1950-2010
« Reply #2 on: December 28, 2017, 03:04:46 AM »
Sure thing.

James Clayton

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Re: Light pollution GIF 1950-2010
« Reply #3 on: December 31, 2017, 08:49:36 AM »
Cool, thank you GrafikDihzahyn.  I just wrote a rather lengthy blog post about it, using the graphic as the highlight:

http://eyesonthesky....iously-WHY.aspx

manreistilles

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Re: Light pollution GIF 1950-2010
« Reply #4 on: January 04, 2018, 02:01:26 AM »
What data is this based on? I'm not aware of many people measuring light pollution in the 50s.

breakinnocor

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Re: Light pollution GIF 1950-2010
« Reply #5 on: January 04, 2018, 06:58:07 AM »
GrafikDihzahyn,Those are great data. The animation certainly has the desired effect. (It makes me sick)

Praveen Mac

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Re: Light pollution GIF 1950-2010
« Reply #6 on: January 08, 2018, 06:32:28 AM »
Great job! Sad to see light pollution growing and Chicago to Milwaukee and Rockford all become white zone amd I see pink inside Chicago. Is that brighter than white?

calbeyrefrows

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Re: Light pollution GIF 1950-2010
« Reply #7 on: January 09, 2018, 03:16:39 AM »
Quote
What data is this based on? I'm not aware of many people measuring light pollution in the 50s.
That's what I was thinking too - what can this LP map possibly be based on? <em class="bbc">Edited to add: If the graphic isn't based upon sound referenced data then it can't be used as a credible outreach / awareness tool in the LP battle.

imasatex

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Re: Light pollution GIF 1950-2010
« Reply #8 on: January 09, 2018, 04:38:37 AM »
Quote
What data is this based on? I'm not aware of many people measuring light pollution in the 50s.
I found out the 50s image is, as well as the others are often, credit as "Historic and anticipated increases in artificial night sky brightness in the United States./NIH." such as here:http://www.wired.com...-pollution-map/What is the 50s measurements based on? Wild guess - an estimate or simple calculation based on population and its density just like the estimate for 2025. If you really want to look at the animation I think it is based on the 1950-2025 data(estimates) not 1950-2010 like the title says./Jake

dedlowsthima

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Re: Light pollution GIF 1950-2010
« Reply #9 on: January 10, 2018, 10:01:42 AM »
Hmm, looks as though this whole animation is based on one data point, from 1997. Not a very solid basis for 75 years of history!

A think that enough time has now passed since  Cinzano's original prediction to say that the extrapolation to 2025 is definitely over-pessimistic -- probably by a large amount.

I have no doubt that the skies in Italy did get significantly worse from 1971 to 1998, but I wouldn't place to much credence in the precise numbers, since the data were obtained by wildly different methods in 1971 and 1998.

My own measurements using identical equipment and methodology over a period of 7 years show no statistically significant brightening of the sky over that period at several sites. However, I have no doubt that there are other sites in the U.S. where the skies did get significantly worse over that period. And no doubt a few where it got significantly better.

pesorramidd

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Re: Light pollution GIF 1950-2010
« Reply #10 on: January 10, 2018, 10:33:16 AM »
A quite noticeable trend over even the past five years is the increasing predominance of full-cutoff fixtures in municipal streets and commercial parking lots (and even many auto dealerships, albeit still very bright).  Nevertheless, there are still too many lighting designers/developers/businesses in thrall with unshielded globe or acorn-style lights.  I am for a few weeks relocated  from N.C. to Salt Lake City, and have every pre-dawn morning for the past two weeks witnessed an egregious side-by-side example of the excellent coexisting with the atrocious when I drop my older daughter off to work at Intermountain Hospital in suburban Murray, Ut.  This is a huge hospital complex with equally huge parking lots, yet the lighting is full-cutoff and enables folks to easily see their way through the labyrinth of approach roads into the hospital complex and through its lots and entrances without fighting any harsh glare.  The city street just outside the hospital grounds and the TRAX (light rail) station across the street from the hospital are, unfortunately, another story: the lighting fixtures are pure harshly bright sodium glare-on-a-stick in the unfortunate style of updated faux gas-lamps.  I have to squint to minimize their blinding glare as I drive past.

My daughter lives in a house up on the "Avenues", which has an elevated view 200 feet above the valley floor with a nice view of downtown and the valley stretching out twenty miles to the south and ring of mountains surrounding the city.  At night, what particularly stands out are the particular streets lined by these hideous unshielded "acorn" or "globe" fixtures, more than commercial business lights themselves.  From a height, it's particularly easy to see which kinds of lights are most visible from even miles away.  To be sure, some usual suspects as some auto dealers and types of commercial businesses are obvious, but unshielded street light fixtures are what really stand out.  Guess what HUGE business fixture is rather difficult to make out at night unless you really look for it?  Intermountain Hospital, even though it has by far the tallest building away from immediate downtown, three or four miles away.  OTOH the rows of sodium streetlights on a few main avenues are obvious miles away.

raposttavers

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Re: Light pollution GIF 1950-2010
« Reply #11 on: January 10, 2018, 02:38:22 PM »
Quote
Tony Flanders wrote:(snip)My own measurements using identical equipment and methodology over a period of 7 years show no statistically significant brightening of the sky over that period at several sites. However, I have no doubt that there are other sites in the U.S. where the skies did get significantly worse over that period. And no doubt a few where it got significantly better.
By any chance, were the observing sites that remained in stasis located in areas that are substantially rural in nature? I understand that there has been a notable population decrease in such areas over the last 10 years or so, and wonder if such a demographic shift could account for your results.

neulosali

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Re: Light pollution GIF 1950-2010
« Reply #12 on: January 12, 2018, 04:56:31 AM »
Quote
<p class="citation">QuoteTony Flanders wrote:

(snip)
My own measurements using identical equipment and methodology over a period of 7 years show no statistically significant brightening of the sky over that period at several sites. However, I have no doubt that there are other sites in the U.S. where the skies did get significantly worse over that period. And no doubt a few where it got significantly better.

By any chance, were the observing sites that remained in stasis located in areas that are substantially rural in nature? I understand that there has been a notable population decrease in such areas over the last 10 years or so, and wonder if such a demographic shift could account for your results. [/quote]

Rural, suburban, and urban. Of those I would say that urban has changed the least in the last 40 years. Cities were saturated with streetlights two generations ago, and if anything lighting practices have improved since then.

Obviously, the biggest change by far has been in areas that were semirural 40-50 years ago and are now solidly suburban. There's quite a lot of those even here in the Northeast, where population has grown fairly slowly over that time span, and many more in the South and the West.

Those outer suburbs degrade not only their own skies, but also surrounding rural areas and even inner suburbs. In fact, I wouldn't be surprised if they're the single biggest factor in aggregate light pollution from a typical metro area. But they're too far from the central cities to have much effect on the central cities.

Obviously, the huge increase in car traffic since the 70s has also been a major effect. Car headlights are one of the very biggest sources of light pollution, probably exceeding even streetlights in outer suburbs.

John Pfister

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Re: Light pollution GIF 1950-2010
« Reply #13 on: January 13, 2018, 05:56:06 AM »
Agreed, Tony... as one living in an area (northern New Jersey) that has gone from semi-rural to suburban over the last 40-odd years, I can testify that the change has been dramatic. The period from the early 1960's to the very early 1980's did not evidence a great deal of change, but from approximately 1982 onwards the skies deteriorated considerably every year, well into the late 1990's, when they appeared to stabilize somewhat.

I was not aware of the contribution of car headlights to LP, thank you for that information... considering the mobile society in which we live, and the ubiquity of the automobile, that LP issue will be "one tough nut to crack", to use the vernacular.

I will say that, overall, the animated .gif so kindly provided by GrafikDihzahyn does, for the most part, mimic closely the spread of light pollution I have observed from my environs here in New Jersey over the years.

Marlon Hilzer

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Re: Light pollution GIF 1950-2010
« Reply #14 on: January 13, 2018, 11:14:18 AM »
Quote
....Obviously, the huge increase in car traffic since the 70s has also been a major effect. Car headlights are one of the very biggest sources of light pollution, probably exceeding even streetlights in outer suburbs.

That may well explain why LP is less after midnight, at least in areas were the traffic gets far less late at night.