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LP study and Tucson

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#1 sg6

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Posted 29 October 2020 - 02:52 AM

Seems Tucson has been dimming its street lights for the 10 nights to help identify sources of LP. Images and measurements being obtained from space.

 

The comparison between normal and reduced illumination are indicating that street lights has minimal effect, basically they are not really polluting much.

 

Main source is all the other junk, billboards, advertisings arrays, illuminated buildings, illuminated parking lots etc.

 

Better say that pollution in this case is not how bright it is at street level but what is going upwards where it should not be. Pollution beig something in the wrong place and if the idea is to illuminate the street and that is all the light does then it is not pollution.

 

Now the catch, it is a BBC link and they have have UK and a non-UK site. All I can supply is the UK link and hope you can see it.

BBC Link

 

The Tucson image with no dimming and dimming doesn't look much different.

The other question: Did anyone in Tucson notice the reduced street lighting?


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#2 ian408

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Posted 29 October 2020 - 03:35 AM

One of the key selling points of the LED conversions I've read about has been dimming lights during periods when fewer people are on the street. I don't know I've ever seen the street lights dimmed on my street :)

 

I live near Mt. Hamilton and the Lick Observatory. For a long time, cities in the county had been installing Low Pressure Sodium lights to aid the observatory in filtering the light out. Since cities have been installing LED lighting, filtering the light out has been much harder.

 

Thanks for the article! It was a good read.



#3 happylimpet

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Posted 29 October 2020 - 03:49 AM

Our streetlights dim considerably at 2330.

 

There is a very slight change in the background level of my subs (like 1%) but I too have concluded that the majority of light polltuion for me comes from other sources. Either that or other streetlights which dont dim - it may just be our street.



#4 George N

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Posted 29 October 2020 - 02:31 PM

One of the key selling points of the LED conversions I've read about has been dimming lights during periods when fewer people are on the street. I don't know I've ever seen the street lights dimmed on my street smile.gif

 

......

LED street lights can indeed be easily dimmed -- and even controlled by a system of sensors and computer programing that could - for example - turn highway lights off if there's no vehicles. I would say that's a nice "feature".

 

For the towns, villages, and city in my area the only "key selling point" for the governments involved was -- reduction in electric and maintenance costs. Any actual impact of the lighting was far from their minds. A group of friends and I tried to get a town that has a nice "public observatory" to at least go with a warmer color. The Town Engineer said we were totally wrong -- the AMA knows nothing about light, etc, -- the Town Board when with his advice.

 

In the city near me - one of the current "issues" in the local news is some group complaining that the street lights in their area are not bright enough -- and that they need MORE lights. Part of it is driven by the lights being out on a mountain curve street leading into the largest "public housing" in the city. It is a dangerous hill.

 

We have plenty of room to go to educate the public on LP issues.


Edited by George N, 29 October 2020 - 02:33 PM.


#5 dustyc

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Posted 29 October 2020 - 02:41 PM

In my Phoenix neighborhood the LED streetlights have a yellowish color. Yet the skyglow continues to get brighter but has a definite white blue tone. I think it is commercial lighting. Areas of largely residential (Fountain Hills, Paradise Valley) have minimal commercial activity and are darker. 



#6 BYoesle

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Posted 18 November 2020 - 01:52 PM

In my Phoenix neighborhood the LED streetlights have a yellowish color. Yet the skyglow continues to get brighter but has a definite white blue tone. I think it is commercial lighting.

The comparison between normal and reduced illumination are indicating that street lights has minimal effect, basically they are not really polluting much.

 

I believe the study highlights the importance of needing to mitigate all sources of light pollution.

 

In 2017 the small City of Goldendale, Washington (population 3400) converted all of their HPS fully shielded streetlights to fully shielded 3000 K LED, and there has been absolutely no decrease in night sky brightness. If anything there is an obvious increase in sky glow that I have noted from my rural location a few km away, and it has been significant:

 

Yakima Goldendale compare HPS v LED.jpg

The "light domes" of Yakima and Goldendale, Washington. Left - July 2017 an aurora display creates the red-purple glow along the horizon. Right - July 2020 air glow creates the faint green glow along the horizon. Mike McKeag

 

The pictures above were taken by Oregon IDA State Coordinator Michael McKeag prior (July 2017) to and after (July 2020) the September 2017 Goldendale 3000 K LED streetlight conversion. They were taken from close to the same location on Dalles Mountain Road looking north north-east. They do not indicate a decrease in the amount of light pollution from Goldendale with the conversion to 3000 K LED streetlights. If anything, the relative brightness of the "light dome" from Goldendale (enacted but unenforced lighting codes) now exceeds that coming over the Simcoe Mountains from Yakima, Washington 75 miles (120 km) to the north. Yakima replaced almost all HPS streetlights with 5000 K LED street lights in 2014, and has no lighting codes at all. Also note the obvious change in the color temperature of the Goldendale light pollution. These images seem to confirm that 3000 K LED street lighting worsens skyglow by a factor of two compared to HPS - and without at least 60% dimming - generally is more damaging to the night sky than previously installed HPS street lighting.

 

 

hps-v-3000k-arrow_orig.jpg

Flagstaff Dark Skies Coalition


Edited by BYoesle, 18 November 2020 - 02:02 PM.

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#7 earlyriser

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Posted 19 November 2020 - 08:43 AM

The growth of light pollution my area appears to be largely from the increased levels of illumination enabled by LED lights.  Several of the commercial properties in my neighborhood have increased how brightly their parking areas are illuminated by what appears to be 2-4X over how bright they were prior to installation of LED lights. The LED streetlights, on the other hand, appear to produce about the same level of illumination at ground level as the old ones. It seems the city is more interested in saving money on electricity, while the private property owners prefer to use this new technology to produce more light. 



#8 Stardust Dave

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Posted 19 November 2020 - 09:34 AM

"In my Phoenix neighborhood the LED streetlights have a yellowish color. Yet the skyglow continues to get brighter but has a definite white blue tone. I think it is commercial lighting. Areas of largely residential (Fountain Hills, Paradise Valley) have minimal commercial activity and are darker." 

 

Fountain Hills is an International Dark-Sky community. smile.gif  

Ironic that my friends that live there have Zero interest in Astronomy. 



#9 dustyc

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Posted 19 November 2020 - 02:26 PM

"In my Phoenix neighborhood the LED streetlights have a yellowish color. Yet the skyglow continues to get brighter but has a definite white blue tone. I think it is commercial lighting. Areas of largely residential (Fountain Hills, Paradise Valley) have minimal commercial activity and are darker." 

 

Fountain Hills is an International Dark-Sky community. smile.gif  

Ironic that my friends that live there have Zero interest in Astronomy. 

I've been out to Fountain Park. There are round concrete pads (maybe a half dozen) on the east side of the park, perfect for sitting a scope yet they're each close by a streetlight! 

They're proud of that dark sky accolade, you'd think they would set aside a small area in the park (or somewhere) with no lights or red ones to promote stargazing. Looking east is pretty decent but west is a total washout from Phoenix.



#10 Stardust Dave

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Posted 19 November 2020 - 03:33 PM

they've got this coming saw this morningsmile.gif

https://darkskycenter.org

 

We'll probably see it finished by the time we are out that way again. Might be years.

Interesting park , to read about the pumps and all.  It was not any special occasion so the fountain was not the 600 feet it can reach.


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#11 dustyc

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Posted 19 November 2020 - 06:31 PM

Wow. waytogo.gif I had no idea when I wrote the above (#9) 

The city of Rancho Mirage has something like that next to their library. Same big Planewave scope! 


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#12 rockethead26

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Posted 20 November 2020 - 10:25 AM

they've got this coming saw this morningsmile.gif

https://darkskycenter.org

 

We'll probably see it finished by the time we are out that way again. Might be years.

Interesting park , to read about the pumps and all.  It was not any special occasion so the fountain was not the 600 feet it can reach.

Looks like it will be a great educational center.



#13 GeorgeLiv

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Posted 22 November 2020 - 09:15 PM

Taking the spectrum of sky-glow has shown (to me at least) that all cities, suburbs and towns in North America nearly have the same lighting sources and practices. This includes Tucson, a city known to have lighting ordinances for decades.

2020 ClearNights compared
 
This indicates (in the least): The lighting industry is selling (and pushing) the same products throughout; and the commercial zones are MAJOR contributors to a city's (or towns's) sky-glow.

Edited by GeorgeLiv, 22 November 2020 - 09:18 PM.

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