Author Topic: What is the worst light pollution source?  (Read 887 times)

Terrance Station

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What is the worst light pollution source?
« on: December 24, 2017, 04:12:53 AM »
Is it street light, residential exterior lights, commercial lighting or some other source?

In seeing the Dark Sky finder map it is clear that all downtown, commercial regions stand out just like search lights in terms of light intensity.  I guess their participation involving light pollution is a significant proportion of the total.  If light pollution would be to be reigned in then commercial lighting may be the logical goal perhaps even more important than street lighting.



Tim Massey

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Re: What is the worst light pollution source?
« Reply #1 on: December 24, 2017, 08:28:19 AM »
Street lighting is probably number one, midsize, but commercial lighting is right up there fairly close, particularly for properties that are known to get large quantities of light through the night.  Those I see becoming the worst as individual companies are automobile dealers, gaming casinos, and movie theaters.

ndesevtenzio

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Re: What is the worst light pollution source?
« Reply #2 on: December 24, 2017, 06:48:06 PM »
I'd thnk it would be auto's and trucks.  Those horizontal light beams sure can get you

ruesonecrai

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Re: What is the worst light pollution source?
« Reply #3 on: December 27, 2017, 11:55:00 PM »
Driving home from Kopernik Observatory (on the NY/PA border south of Vestal, NY) I can look out at 95% of the local LP sources when I hit the top of the hill crest before driving down into the urbanized river valley. It is quite apparent that streetlights are number 1, although the single brightest light source comes from athletic field lights. If these street lights were shielded so that I could not directly see the bulbsfrom hundreds of feet higher - and I could only see the lit ground and roads - there would be a LOT less sky glow, vehicles or not.

On the other hand, our latest bright light sources are: flaring gas fracking wells in PA. I could see two of them burning away as I drove home a week ago. They not only light up the sky, they add flickering light! ....still nowhere near as bad as the valley streetlights. If the river valley fogs up when it is still clear up on the mountain, we get around 21.3 mag/sq-arc-sec at thezenith(SQM reading), while when there is no valley fog, we get around 20.8 - quite a difference..... enough to make the Milky Way go from being 'dramatic', to 'there, but not nearly as noticeable'.

Jaye Agting

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Re: What is the worst light pollution source?
« Reply #4 on: December 29, 2017, 10:25:19 PM »
The worst is the mercury and sodium vapor street lights,next is architectural and advertising. It would be nice to have laws that turn off the advertising and lit up buildings atsay midnight every night. Ialways marvel at the huge lighted parking lots thatstay lit all night after businesses close and the lots sit empty. We are not really serious about saving energy yet.

coreanoguf

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Re: What is the worst light pollution source?
« Reply #5 on: December 29, 2017, 11:50:03 PM »
Cities--never go anywhere near them. They are bright and dangerous.

Dark skies.

Jack

compstifcolpai

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Re: What is the worst light pollution source?
« Reply #6 on: December 30, 2017, 04:09:04 AM »
On the plus side, the "Put a Casino at the Race Tracks" referendum was defeated......there's one within about 5 miles of our dark site as the crow flies......

Jeff Swan

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Re: What is the worst light pollution source?
« Reply #7 on: December 30, 2017, 10:30:33 AM »
Lights in general. If it's not shielded, dimmed and pointing down; or red, then I hate it.

Nicholas Becker

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Re: What is the worst light pollution source?
« Reply #8 on: January 07, 2018, 11:36:04 PM »
Actually, after thinking about it for a while, the worst light pollution is that which is located within a couple miles of me! The closer, the worse it is.

behelphyri

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Re: What is the worst light pollution source?
« Reply #9 on: January 08, 2018, 08:22:27 AM »
Quote
The worst is the mercury and sodium vapor street lights,next is architectural and advertising. It would be nice to have laws that turn off the advertising and lit up buildings atsay midnight every night. Ialways marvel at the huge lighted parking lots thatstay lit all night after businesses close and the lots sit empty. We are not really serious about saving energy yet.


Some residential areas are infested with this particularly horrible form of street lighting, purportedly to add a fancier architectural touch to a development, but which at night become a paradigm example of wastefully inefficient, blindingly glaring ugliness-on-a-stick. Unlike a standard cobra-head streetlight, it's impossible to shield against one of these monstrosities without black-painting over most of the light (a great idea, but doubt they'll let you do that). Yesterday I spent most of the day out at a park in Cary refereeing a soccer tournament, and during a break between games took a stroll down a leafy greenway trail that within a quarter-mile, passed through a new neighborhood literally infested with these glareballs-on-a-stick - there were several within direct sight of every house. ARRGH!Attached Thumbnails


bayretide

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Re: What is the worst light pollution source?
« Reply #10 on: January 08, 2018, 07:14:19 PM »
Streetlights. As a part of my job I fly in a small airplane to observe traffic. After sunset the first thing to show up (brightest, but very localized) is car dealerships, then athletic fields, then hundreds of streetlights. The sheer number of streetlights and their widespread (mis)use gets them the #1 spot

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Darkz Tousa

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Re: What is the worst light pollution source?
« Reply #11 on: January 09, 2018, 04:27:32 AM »
Quote
Quote

The worst is the mercury and sodium vapor street lights,next is architectural and advertising. It would be nice to have laws that turn off the advertising and lit up buildings atsay midnight every night. Ialways marvel at the huge lighted parking lots thatstay lit all night after businesses close and the lots sit empty. We are not really serious about saving energy yet.


Some residential areas are infested with this particularly horrible form of street lighting, purportedly to add a fancier architectural touch to a development, but which at night become a paradigm example of wastefully inefficient, blindingly glaring ugliness-on-a-stick. Unlike a standard cobra-head streetlight, it's impossible to shield against one of these monstrosities without black-painting over most of the light (a great idea, but doubt they'll let you do that). Yesterday I spent most of the day out at a park in Cary refereeing a soccer tournament, and during a break between games took a stroll down a leafy greenway trail that within a quarter-mile, passed through a new neighborhood literally infested with these glareballs-on-a-stick - there were several within direct sight of every house. ARRGH!

I live near Dixon and major remodel and new streets in downtown of Dixon. It look nice but I am not happy


nasapehe

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Re: What is the worst light pollution source?
« Reply #12 on: January 11, 2018, 02:37:18 AM »
Quote
At least Mercury and Sodium vapor lights can be filtered out. My concern is that full spectrum LED lights will replace older lights and with the lower wattage, cities will seek to erase the last star from the skies with the energy savings.
Yes. The broad spectrum lights are much worse.

Bill Godschalk

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Re: What is the worst light pollution source?
« Reply #13 on: January 12, 2018, 12:41:24 AM »
Quote
Quote
At least Mercury and Sodium vapor lights can be filtered out. My concern is that full spectrum LED lights will replace older lights and with the lower wattage, cities will seek to erase the last star from the skies with the energy savings.
Yes. The broad spectrum lights are much worse.
The surprising (& sad) thing about the "high efficiency" LED lights is that they cost more, and only last about 1.5 times as long as traditional Mercury/Sodium vapor lights. They are faster & easier to replace the bad units, and are easier to "program" where the light goes, but overall not really a good option. Mercury/Sodium/LED streetlights are "supposed" to be handled as Hazardous materials, because of the rare earths elements involved in them. LED's are particularly bad because of the Haz mat involved in creating them in the first place. Very few actually are handled that way. Most wind up in the dump or at best the recycling center.

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anstirabnas

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Re: What is the worst light pollution source?
« Reply #14 on: January 12, 2018, 10:58:02 AM »
Quote
LED's are the current politically correct savior of the planet but as far as I know the actual efficiency of LED's has not yet passed that of high or low pressure sodium lights. In fact I am not sure that LED's have passed high efficiency florescents or metal halide lights.

From what I have read LED lights are not at the point where either cost or efficiency merits wholesale adoption for replacement of street lights.


The above statement is a seriously inaccurate misunderstanding of the relative efficiencies of LEDs vs the other named light sources, both in terms of energy and cost. The reasons LEDs are more efficient light sources are closely tied to why they are potentially both boon and bane for astronomy (back to this in a minute). Rather than nebulously saying "I read this somewhere", here's a couple of links to enlightenment on the subject:
1) For a good self-contained technical explanation (requires some modest scientific literacy, but not a physics degree):
Comparison of LED v Other light sources including HID
2) For a comprehensive overview of the characteristics and advantages vs disadvantages of various types of street lights:
Street lighting technology comparison

Here's the probable basis for your claim that LEDs are a less efficient source than high or low pressure sodium lights or metal halide lights, extracted from a chart you'll find in the first chart I cited above.

Light Source:         Lumens/Watt
Low-Pr Sodium       130
High-Pr. Sodium       110
Metal Halide          90
T8 Fluorescent(3000K) 78
LED                100

Measured in Lumens/Watt, LEDs would indeed seem to fall short of sodium lights by 10 to 30%. However (and here's where relevant tie-back to astronomy begins) - what actually does a "lumen" represent? First, lumens are a measure of the total light produced by a lamp, without taking into consideration how efficiently it's directed. Because sodium lights emit in a 360 degree sphere vs LEDs being directionally limited, raw lumens/watt is a misleading measure. (That is the characteristic of LEDs that is potentially good for astronomy). Also, lumens are a photopic measure (response by cones responsible for color vision), yet sodium lights emit most of their light within a narrow spectrum (good for ability of astronomers to filter out those wavelengths), but actual street lighting conditions are in the low-medium range of mesopic (mixed rods and cones) vision, which the full visible spectrum output of LEDs covers more effectively (and accurately) - hence pupil lumens/watt is a better measure (bad for ability of astronomers to filter out LEDs). I'll refer you to the first article for the articulate in-depth explanation of what "pupil lumens" is and why it's a better measure of mesopic vision lighting effectiveness, but measured this way:

Light Source:         Pupil Lumens/Watt
Low-Pr Sodium 29.9
High-Pr. Sodium 68.2
Metal Halide134.1
T8 Fluorescent(3000K) 87.89
LED 200

...which is why an LED streetlight can produce the same effective amount of light for lower wattage than low or high-pressure sodium lights and so on, AND with much more accurate color rendition (meaning people can see things better with LEDs, even using less raw wattage). Unlike sodium street lights, LED street lights can be adjusted to be brighter or dimmer (less energy), instead of same brightness e.g. at 3am when few people are about. (Good for astronomy, if the utility intelligently uses this feature).