One more thing to worry about: cloud light pollution amplification

Chicago City Lights Photograph by Jim Richardson - National Geographic 2008 - Chicago at night burns bright under blankets of clouds. Much of the glow escapes from streetlamps, including clear, Victorian-style lamps good for creating atmosphere but poor for harnessing today's extra-bright bulbs. - Click for details and to get a print

Clouds amplify ecological light pollution

The brightness of the nightly sky glow over major cities has been shown to depend strongly on cloud cover. In natural environments, clouds make the night sky darker by blocking the light of the stars but around urban centers, this effect is completely reversed, according to a new study by a group of physicists and ecologists at the Free University of Berlin (FU) and the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB).

“We found that overcast skies were almost three times brighter than clear at our rural location, and ten times as bright within the city itself,” says the lead author of the study, Dr. Christopher Kyba, physicist at the Institute for Space Sciences at the FU. Their research was reported on March 2nd, 2011, in the open access journal PLoS ONE.

“The astronomers who founded the study of light pollution were concerned with how sky glow obscured the stars on perfectly clear nights,” says Kyba, “and researchers studying the potential influences of sky glow on human or ecosystem health often cite the results from satellite measurements taken on clear nights. What our study shows is that when considering biological impact on humans and the environment, the amplification of light pollution by clouds is large, and should be taken into account.”

The study compares measurements of clear and cloudy sky brightness data taken using “Sky Quality Meters” during five months in the spring and summer of 2010. Two monitoring stations took data at locations 10 and 32 km from the center of Berlin. “Recognition of the negative environmental influences of light pollution has come only recently,” says Dr. Franz Hölker, ecologist, study author, and project leader of Verlust der Nacht (VdN – Loss of the Night).

“Now that we have developed a software technique to quantify the amplification factor of clouds, the next step is to expand our detection network. The Sky Quality Meter is an inexpensive and easy to operate device, so we hope to recruit other researchers and citizen-scientists from around the world to build a global database of nighttime sky brightness measurements.” The authors encourage those interested in participating in such a measurement to contact them at


The research was funded by two interdisciplinary projects, MILIEU ( and VdN ( An interdisciplinary project of the FU, MILIEU – center for urban earth system studies, was initiated as a focus area at the FU, funded by the German excellence initiative, in order to investigate the bottom-up and top-down interactions between urban agglomerations and the climate and environment. The VdN project, funded by the German Ministry of Education and Research, is specifically devoted to quantifying light pollution and investigating its impact on humans and the environment.

Citation: Kyba CCM, Ruhtz T, Fischer J, Ho¨ lker F (2011) Cloud Coverage Acts as an Amplifier for Ecological Light Pollution in Urban Ecosystems. PLoS ONE 6(3):e17307.doi:10.1371/journal.pone.0017307


Competing Interests: The authors have declared that no competing interests exist.

Funding Statement: This work was supported by the project Verlust der Nacht (funded by the Federal Ministry of Education and Research, Germany, BMBF-033L038A) and by MILIEU (FU Berlin). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Contact information:

Dr. Christopher Kyba

Freie Universitat Berlin / IGB

+49 30 838 71140

Available weekdays 1pm-4pm (CET), evenings possible by email arrangement


This press release refers to upcoming articles in PLoS ONE. The releases have been provided by the article authors and/or journal staff. Any opinions expressed in these are the personal views of the contributors, and do not necessarily represent the views or policies of PLoS. PLoS expressly disclaims any and all warranties and liability in connection with the information found in the release and article and your use of such information.

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Tom T
March 3, 2011 3:21 pm

Is it kind of hard to see the stars with lots of clouds even if they don’t make it brighter.

March 3, 2011 3:22 pm

Light pollution? Actual problem or a clever pun? You decide.

March 3, 2011 3:32 pm

Anybody who has been outdoors at night in a city knows the sky is brighter when it is cloudy than when it is clear. Who exactly is paying for this?

March 3, 2011 3:32 pm

This is news? I was 12 years old playing outside in Denver colorado and noticed on an overcast night how much easier it was to see everyone when we were playing Hide-and-Seek. That was over 30 years ago.
Maybe I should apply for a retro-active grant?

Brian H
March 3, 2011 3:32 pm

Short of installing shades/reflectors on all streetlamps, there doesn’t seem to be any sort of remedy.

Grumpy Old Man
March 3, 2011 3:39 pm

This does not surprise me. I’ve had to install blackout blinds in my bedroom to keep out light pollution and get a good night’s sleep, otherwise I wake through the night thinking it’s dawn.
Anyone else suffer from lack of sleep due to light pollution?

Rhoda R
March 3, 2011 3:41 pm

I’m not sure that I understand the negative impacts of light pollution. I know that I can see better when I return home after dark if it’s overcast, but I don’t see the problem with that.

Keith Minto
March 3, 2011 3:43 pm

“Ecological light pollution” is a quality judgement and hardly has a place in the title of a scientific paper. Light scatter may be closer to the mark. As a sometime amateur astronomer I can appreciate clear skies, but don’t start a paper with an obvious bias.

March 3, 2011 3:46 pm

What does this do to Hansen’s night-light brightness measure of the urban heat island effect?

March 3, 2011 3:49 pm

Is this for real. This is 2011 and people are getting paid to tell us that in the city clouds make it brighter. Dah Dah Dah. I dont think this is ground breaking news.
News flash : WHen there are no clouds in the sky it doesnt rain. WHen there are clouds in the sky it sometimes rains. Can i get a grant to study this?

David S
March 3, 2011 3:52 pm

No S*** Sherlock!

David Y
March 3, 2011 3:56 pm

I’m guessing that the next set of taxpayer-funded studies will examine how the ecological balance has tilted so that former daytime-only predators can now hunt effectively at night, ‘catastrophically changing’ the ecosystem (the scientists will have forgotten about how day length changes over the course of a year–it’s called ‘seasons’).
Then there will be studies linking this to crime (more? less? The answer is cloudy… 😉
Then there will be something about clouds converting light to heat and melting the glaciers.
And so on it goes. Sheesh.

March 3, 2011 4:01 pm

Here in Florida, I have been looking at highway cloverleaf lighting. It seems to me that a great deal of energy is wasted illuminating highway ‘landscaping’ (IMHO, that is an sad misnomer) and that a back-of-the-envelope estimate would be 60-75% wasted power lighting things that would prefer not to be lighted at night.

Bob Diaz
March 3, 2011 4:02 pm

For what it’s worth, anyone who lives in a big city and looks up at night can see the fact that light from the city goes upward. I even shot a timelapse video of it:


I’d really love to know what harm comes from this? If you want to see stars, go to the countryside.

March 3, 2011 4:04 pm

“The astronomers who founded the study of light pollution were concerned with how sky glow obscured the stars on perfectly clear nights,”
Astronomers, who needs them 🙂

Theo Goodwin
March 3, 2011 4:04 pm

On the internet, there is an image of a stitched together map of artificial light seen from space at night time. It is also a map of human prosperity. I am somewhat sad to say that my neighborhood, I4 across central florida, is prominently displayed. Yes, there are lots of lights along I4 and Florida’s low flying clouds reflect them powerfully. It is difficult to see stars on clear nights. However, it is hard to see how the light reflected from clouds would be noticed by critters travelling among the lights on the ground.

March 3, 2011 4:05 pm

So What?

Gary Hladik
March 3, 2011 4:11 pm

This is actually a beneficial effect in suburbs without streetlights, such as Saratoga, CA: more useful light for the same energy use, without the capital outlay for more streetlights. We need more night clouds.
Except on meteor shower nights, of course. 🙂

Gary Hladik
March 3, 2011 4:14 pm

Keith Minto says (March 3, 2011 at 3:43 pm): ‘“Ecological light pollution” is a quality judgement and hardly has a place in the title of a scientific paper.’
Next thing you know, the EPA will go after the moon for “light pollution”. 🙂

March 3, 2011 4:17 pm

It has to be a joke right?
Light pollution ??? hahahahahaah!!!

March 3, 2011 4:20 pm

Same thing as animals exhaling produces pollution ehh …

Robert of Ottawa
March 3, 2011 4:20 pm

Astronomers are rightly concerned about light pollution. However, …. WE’RE ALL GONNA DIE!

March 3, 2011 4:25 pm

Those researchers never heard of the light conditions inside the polar circles. Damn sun is polluting 24/7 for 6 months in a row in these area of the globe.

March 3, 2011 4:30 pm

My wife and I have an older Bausch & Lomb 6000 Telescope and we happen to live a bit out in the country- no streetlights, box store parking lot lighting. etc- which makes viewing the stars more enjoyable at our place then in the SF BAY AREA. If your really into star gazing you might find this of interest- “Stargazers now have their Graceland. The Channel Island of Sark, located 80 miles south of England, has been designated as the world’s first dark-sky island.” as noted-

March 3, 2011 4:31 pm

Could there be a light dimmer company lobbying governments for cities to install dimmers on cloudy nights?
That should be a good place to put a change a light bulb joke…
Q. How many climate scientists does it take to change a burnt light bulb?
A. None. The computer model says the light is not burned.

March 3, 2011 4:35 pm

streetlights that are not properly shaded RUIN your night vision.
streetlights that are not properly aimed- ruin the night sky
i’m an amateur astronomer and quite honestly, i WISH that my city would turn off ALL street lights at night, in all honesty they are essentially USELESS now.
they came about due to horse and buggy’s not having lights at night
cars not having headlights
now every Vehicle on the road- except for bicycles- has headlights which more than adequately light the area in front of the vehicle to drive.
streetlights do not prevent crimes in homes- statistically most breakins occur during the day when the people are not home.
streetlights RUIN the night sky. i WANT to see all the stars in my area you can barely see orion, you CANNOT see the little dipper, etc.
plus in this cost conscious time, the money the city would save is significant if they just TURNED off the lights.
sorry pet peeve of mine.

Mike Davis
March 3, 2011 4:35 pm

Light Pollution has been a discussed fact for many years. I just do not see the justification to spend money to study a known problem! There are cities and neighborhoods that regulate “Light Pollution”. It is an environmental problem!

March 3, 2011 4:37 pm

What are these “scientists” [?] on about?
What is their point about a subject which anybody with eyesight and around even a very small settlement knows that the town lights let alone a large city’s lights reflect from clouds at night. Nor do they define the so called biological effects which any shift worker can describe in detail.
And of course the mandatory mention of the “ecosystem health” which must be worth another 10% in grant money.
Thirty years ago late on a pitch black mid winter night with incredibly clear air under a total cover of low cloud over the vast flat grain fields of western Victoria in Australia’s south east I counted and identified some 20 odd towns and small settlements just from the light from each of those towns reflecting from under those low clouds.
Those towns and settlements were scattered in a radius of up to nearly 100 kms from where I stood.
And have they and Hansen with his population density for UHI purposes based on the satellite derived light intensity from city, town and settlements taken into account that Australia for instance, has a regulation that requires all street and publicly lighted venues to have a 90 degree cutoff , ie; a cover over the upper part of the light source that restricts the lighting to no more than the level of the horizon and below.
This is done for better lighting efficiency and to reduce light pollution.
Also many small settlements across Australia’s vast and sparsely settled areas and outback towns which are far removed from any grids use diesel powered electric supplies.
To conserve the very expensive diesel fuel which must be transported often some hundreds of kilometres, the street and public lighting is often switched off at around 10 pm in these small outback towns and settlements.
Both of these factors will distort any calculations which are almost invariably based on the USA experience without taking into account the often vastly different circumstances arising in other countries.
But, hey , this is Climate Science where accuracy does not matter.
Just so long as the claims of the AGW ideology can be maintained.

March 3, 2011 4:43 pm

I’ve done a number of lighting retrofit projects for outdoor areas such as parking lots, truck and rail terminals and other similar types of areas. What I learned was that the more “light spill” from a fixture, the less efficient the fixture. In other words, the more one can keep the light on objects being lighted, the less energy required to drive the lighting system.
I’ve heard the term “light pollution” for years, but I’ve always believed the phrase came from a bunch of tree huggers. My focus has always been to provide my clients with efficient lighting systems … not green systems. As for clouds increasing the amount of light in the city … Duh!

March 3, 2011 4:45 pm

Light pollution is one of those subtle things that everyone should consider, but few city-dwellers are at all familiar with the night sky as it should be seen, so they ignore it.
When I was a child, it was common for people to throw their garbage from fast food trips out the car windows, to blow around on the sides of the highways. I grew up in Oregon, so this rapidly became an eyesore. To the extent that you would literally get trash-drifts just like snow-drifts along the sides of the I-5. Oregonians, being a fairly qwirky bunch as environmentalists go, created a campaign called, “Keep Oregon Green”, and hence the freeways were cleaned up. I was just a kid, and this is how I remember it, perhaps someone older can add more to the story…
The point is light pollution has crept up on humans in much the same way as those drifts of trash on the side of the highway. Sure, we can get by with that trash there, but the beauty of where we exist is tarnished and lost as a result. It is true that extra light around cities can actually help. Cities that are better lit generally have fewer violent crimes against the typically victimized groups (women/children). So extra light in cities is good for humans.
I invite anyone in this thread who scoffs at light pollution being a problem to stay up a couple of nights staring at the open sky somewhere thousands of miles away from a major city. Try Alaska or South America for best results. Or if you’re a sailor, try the middle of the pacific.
I’d wager it might move some of you to tears. Yeah, we can get by with more light in cities, but do you really want our future city generations to have no concept of our place in the universe? Light pollution should be minimized whenever possible. The night sky is a treasure that inspires kids and humbles humanity.

David Walton
March 3, 2011 4:48 pm

This blog title should read “One More Pile Of Fear Mongering And Fraudulent Junk Science From Unscrupulous Money Grubbing Con/Shakedown Artists Posing As Scientists”.
But hey, maybe it is just me.

March 3, 2011 4:49 pm

Brings this to mind.

March 3, 2011 4:50 pm

I have stopped to give a f. because the amount of lighting screws up stargazing anyhow and adding clouds to the pot doesn’t really change the fact of urbanization one iota.
Although I think it is not too wise to use greenie street lamps since when there’s low hanging clouds those parts that use those energy saving lamps lights up like day and it screws with the birds and the rest of the wild life garbage-left-over-critters that has taking up civilization. But it’s not only the life that likes the old lights but, apparently, plants, like trees, seem to like the sodium crap better as well. So how green is it to go energy-save lighting really?

March 3, 2011 4:51 pm

The German Excellence Initiative, really takes off.
Well, however, I mean what is the sense behing that?
If it were at least a result of too much man-made CO2 …

March 3, 2011 4:53 pm

Oh Mie, oh my. Riccatti-Bessel Functions of the even and odd order. It was bad when I was growing up. It is absurd now anyplace near a city. Why its gotten so bad in the Boston area, we are lucky to see the sun sometimes. Walk around with SPF 30 at midnight. OK, so I exaggerate a bit, but seriously, astronomy around here is out of the question other than solar stuff. Most of it could be reduced a bit without loss to safety. You really do not need a big bright high pressure sodium lamp every couple hundred feet. Maybe something, but a high pressure sodium job burns electricity and generates way too much light to be really useful.

It's always Marcia, Marcia
March 3, 2011 4:54 pm

What a pitiable waste of thought worry over light pollution is.

It's always Marcia, Marcia
March 3, 2011 4:55 pm

Gary Hladik says:
March 3, 2011 at 4:14 pm
Keith Minto says (March 3, 2011 at 3:43 pm): ‘“Ecological light pollution” is a quality judgement and hardly has a place in the title of a scientific paper.’
Next thing you know, the EPA will go after the moon for “light pollution”. 🙂
Then will come the taxes.

March 3, 2011 4:56 pm

Overbearing Air Raid Warden (heard in every WWII-era Looney Tunes cartoon):
Overbearing EPA light “pollution” regulator (coming soon):

March 3, 2011 5:16 pm

Perhaps a city could turn its street lights down a bit on cloudy nights and save the tax payers some money without reducing safety.

March 3, 2011 5:25 pm

I thought I’d seen spectacular cloud-lit night skies in San Francisco particularly but my sense of crazy nighttime weirdness produced by airborne water increased the first time I saw a snowstorm when living at 120th Street and Amsterdam in the Morningside Heights area of Manhattan.
Snowstorms there produced a bright orange night sky in upper Manhattan as I have never seen elsewhere.

March 3, 2011 5:30 pm

researchers studying the potential influences of sky glow on human or ecosystem health often cite the results from satellite measurements taken on clear nights. What our study shows is that when considering biological impact on humans and the environment, the amplification of light pollution by clouds is large, and should be taken into account
It would be nice if they actually qualified that “biological impact” by citing examples and quantified the effect of the amplification of light pollution. Are they saying summer in the far north/south or full-moon nights are bad for humans and the environment? I mean, the midnight sun is about as much light pollution as you can get, right?
Yes, there’s light pollution. Personally, I like stargazing, but I find light pollution comes in handy when walking along an unlighted street during a moonless night. It lets me keep a distance between myself and any unleashed dogs or potential muggers. So until they come up with something more than handwaving about “negative environmental influences of light pollution,” I’ll take urbanization and prosperity. Thank you.

Pamela Gray
March 3, 2011 5:55 pm

Please tell me this is an early April Fools day joke. Or an episode of the Simpsons. Or maybe a really bad reality TV show. This can’t be serious research.

Rhyl Dearden
March 3, 2011 5:57 pm

Re biological impact: in Perth, Western Australia, and no doubt in other cities on the coast, seagulls work at night feeding fon the moths circling the street lights. Don’t know if they sleep during the day but their night-time feeding stations are probably more efficient in providing food, so they could just stand on one leg and put their head under their wing.

It's always Marcia, Marcia
March 3, 2011 6:01 pm

I am certain there is increase in car break ins, assault, rape, mugging, hit by cars, when there is no street lights.
If you like looking at stars that much you can sell your house in the city and move to a remote countryside home.

March 3, 2011 6:02 pm

For all those unfamiliar with this issue, it is very real and not trivial. Please visit the International Dark Sky Association to learn more:
“IDA is the recognized authority on light pollution. Founded in 1988, IDA is the first organization to call attention to the hazards of light pollution, and in 22 years of operation our accomplishments have been tremendous. We promote one simple idea: light what you need, when you need it. We know some light at night is necessary for safety and recreation. We work with manufacturers, planners, legislators, and citizens to provide energy efficient options that direct the light where you want it to go, not uselessly up into the sky.”
This is a major problem not only for astronomers, but everyone as bright night skies impact your health (affecting circadian rythms, melatonin production, eyes, etc.), wildlife, not to mention study after study have shown more light doesn’t drop crime etc. but just wastes energy and money.
The night sky is as much a part of the natural environment as any other and deserves protection. Today millions upon millions growing up in the cities have never even seen the Milky Way or a truly dark sky and people are as awed by a spectacular star studded dark night sky as they are when they see other natural wonders.

March 3, 2011 6:06 pm

“plus in this cost conscious time, the money the city would save is significant if they just TURNED off the lights.
sorry pet peeve of mine.”
Where I live it’s pitch black outside unless there is a bright moon and no clouds. I’m in the middle of nowhere, though, so this is generally not a problem.
The city is a different story. Do you truly not realize what you’re asking? I can’t honestly believe that you do.

March 3, 2011 6:06 pm

Chicken little: “The sky is clouding! The sky is clouding!”

March 3, 2011 6:10 pm

We need to cut these people off. Like many others, I figured this out long, long ago and nobody took taxpayer money and gave it to me.

March 3, 2011 6:11 pm

This just in: When you pile garbage from the city into a big pile, it stinks to high heaven!

March 3, 2011 6:12 pm

Ah yes, more worried about heat than cold, more worried about light than darkness. I remember back when society was misguided and thought that the discovery of fire was actually a good thing.

March 3, 2011 6:18 pm

Who funded these idiots for such a non-study. OK. Let’s talk about the amplification factor of the clouds. Do we start out with X lumens, and wind up with 2X lumens? Is there a multiplier effect in there somewhere? This is garbage.
Studying influences of sky glow on human or ecosystem health is really reaching. Academics are really getting desperate for something to study.
Why don’t they go out and study ant hill pollution, and come up with an answer for the unwanted migration of fire ants or African killer bees?
What we are getting from academia is rubbish.

March 3, 2011 6:20 pm

Get your night time street light cool guy sun shades here at the NASA fund the gobal warming grants center.
FBI style , DEA style, cool Jet Jockey style. $19.98 or two for $19.98 plus shiping.

March 3, 2011 6:24 pm

From Wordweb –
verb: amplify
1. Increase in size, volume or significance
2. To enlarge beyond bounds or the truth
3. Exaggerate or make bigger
4. Increase the volume of, “amplify sound”
blow up, exaggerate, expand, hyperbolise, inflate, magnify, overdraw, overstate

Pamela Gray
March 3, 2011 6:26 pm

Even Sears Family Photos R Us know about this and they get paid minimum wage to know it.

March 3, 2011 6:27 pm

Mohib says:
March 3, 2011 at 6:02 pm

The night sky is as much a part of the natural environment as any other and deserves protection. Today millions upon millions growing up in the cities have never even seen the Milky Way or a truly dark sky and people are as awed by a spectacular star studded dark night sky as they are when they see other natural wonders.”

Oh, come on. Put your problem into perspective. Millions of youth sacrifice their virginity every day. This has to be shocking to you.
Less than dark skies are a problem? Get serious. There are real problems in the world, and moaning about a non-problem like less-than-dark night skies only trivializes all of us.
Get real.

March 3, 2011 6:29 pm

North Korea has this aced, you guys should just move there.

March 3, 2011 6:32 pm

In WW2 the blackouts were dreaded as a sign of impending bombs. People yearned for the time when city lights would return as a sign of peace:

Now we’re going to get blackouts again under the marauding enemy army called EPA. Only this time we won’t be allowed to sing about the return of light, because the marauding enemy army is a permanent occupation force.

March 3, 2011 6:35 pm

I don’t think they will find much of a market for their brightness meters. One man’s light pollution is probably 100 mens’ life saving light. Who wants to turn off the lights or get rid of the clouds? If you want to see the sky clearly, get away from the light source and above the clouds and haze layer.

March 3, 2011 6:41 pm

The problem is overprescription of outdoor lighting in the name of safety gone berzerk.
There is also a “keeping up with the Jones” glare problem, where one place has more lights installed, then adjacent areas are hit by the glare and have to upgrade thier light output in order to see again.
It all costs $$, and a lot of outdoor lighting is pure overkill.
10% of all electricity produced goes to nightime lighting, and at least half of it is pure waste.
You have no say in it, as the 1910’s saw street lighting ordinaces which have never been challeneged, but you subsidize it.
Enjoy paying for lighting you cannot switch off.
Have a look at the Earth from Space at night.
Astronomers, professional and amatuer, have known about this problem for decades.
I’m happy to see WUWT tackle this issue.

March 3, 2011 7:32 pm

Let’s get GE right onto that problem. A little of your tax money thrown their way every year and they might eventually come up with a solution.

March 3, 2011 7:34 pm

Brian H says:
March 3, 2011 at 3:32 pm

Short of installing shades/reflectors on all streetlamps, there doesn’t seem to be any sort of remedy.

Every time there’s a recession or energy shortage, Towns in New England talk about shutting off some streetlights, and several have. (And some just fail but don’t get fixed.)

March 3, 2011 7:47 pm

“What our study shows is that when considering biological impact on humans”
What biological impact on humans? I’m asleep at night. who cares if it is light enough to see your hand in front of your face. Let’s try adaption if it is a real problem. Pull the curtains.

March 3, 2011 7:50 pm

Skeptic says:
March 3, 2011 at 4:05 pm
> So What?
Inasmuch as this is a science blog, I for one appreciate the several comets, meteor showers, and an occasional aurora I could watch from home. During Comet Hyakutake’s apparition I lived in a house with windows on three walls of the bedroom, so we could see most of it from bed.
One feature about our property on Mount Cardigan – we can’t see a street light from the yurt.
When I was in college in Pittsburgh in the early 1970s, I figured it was a good night when I could see five stars.
You’re welcome to have no interest in that stuff, but I don’t see how someone can be disinterested in natural wonders yet be interested in a science blog.

Dr. Dave
March 3, 2011 7:52 pm

Geez…”light pollution” makes my blood boil. I live in northern NM, away from the city and in an area without any street lamps. On a moonless night it’s darker than the inside of your hat. I received a notice from a law firm that alerted me that I was to immediately remove the flood lamps mounted on my garage. I called the local covenant compliance officer and explained that I have lived in this house for 16 years and the installed lights were there when I bought the home and were most likely there when the house was built in 1977. No matter. The local covenant board had issued new rules regarding outside lights. I explained that I only use these lights about once a week for about 5 minutes when I take my trash to the street and that none of my neighbors had ever complained. No matter. The covenant compliance officer had cruised the neighborhoods and was citing everyone with exposed flood lamps. It seems a couple of avid skywatchers sit on the community board and they don’t want THEIR night skies trashed by home owners making use of their own property. So I went out and unscrewed the flood lamps and thereby averted legal action. This is personal to me because a few months later I was taking my recycling out to the street in the pitch dark, tripped, fell and broke a rib. I remember laying on my back that cold November night thinking “Gee…the night sky sure is beautiful!”.
Because of these elitist amateur astronomers I’m denied adequate lighting just to illuminate the area from by backyard to the street (maybe 150 ft) for a few minutes once a week. I am denied safety lighting of MY OWN property because these damn hippies “treasure their night skies”. Hey, I like the vivid, dark night skies, too. But this is MY property and it’s not like a WalMart parking lot. Out of 2,700 homes in this area I would estimate there are probably about 50 or 60 amateur astronomers out here…but a few of them are on the board and set the rules.
I already have a generator. I’m going to buy a couple sets of those portable construction spotlights. These are “portable” and therefore not covered by the covenant. Come summer I will grant my girlfriend her wish of being able to garden after work at night! They picked the wrong the fight.

March 3, 2011 8:04 pm

Light is NOT pollution.

nano pope
March 3, 2011 8:15 pm

Makes me think, are the effects of the moon and stars heating the earth at all at night? Anyone know the watts/m^2 of starlight and moonlight?

Richard Patton
March 3, 2011 8:22 pm

What most of the posters are deriding is the fact that someone got grant money (read taxpayer money) to prove the obvious. But it is a fact that some businesses do overkill. Tri-Met the Regional transit agency has a bus “barn” a couple of miles from where I live and at night, even when it is clear, their lights are so bright that residents within a couple of blocks can read a newspaper on their back porch. In Chehalis Washington there is a Car Dealership alongside I-5 who’s security lights are so bright that they nearly blind southbound drivers.

March 3, 2011 8:31 pm

Next we’ll have electricity when they want, no lights at night so criminal can truly roam free, water once month etc… but all subscription to public utilities will be going up significantly and no opting out. That’s progress… I mean climate progress type… LOL

Zeke the Sneak
March 3, 2011 8:32 pm

Mining the earth’s crust damages it and it must be put back the way it was.
Drawing from and contributing to the earth’s atmospheric gases like any other life form is pollution.
Using water causes shortage and is only to be done at need, to be determined by authorities.
Utilizing electricity, though it is the prime force found throughout the universe and is efficiently and cleanly provided by natural resources, is to be eliminated.
Now, lights…at night. At least the Puritans only frowned at extramarital sex and working on Sundays. I don’t know what to say about these eco-puritans except heaven help you if you let them direct policy.

John Trigge
March 3, 2011 8:50 pm

Where I live, in South Australia, we have to suffer a regular, 28-day cycle of night-time total darkness, moving through extremely bright nights then back to darkness again. I request a large amount of money be granted to me to study this light pollution.
I blame NASA as one of their moon landers must have left the lights on.
The night sky on a moonless night out in the Pacific Ocean (from the rear of a darkened destroyer) is mind-blowing.

Fred Souder
March 3, 2011 8:54 pm

Ric Werme,
I have to think that Sceptic’s “SO WHAT” was referring to the study, not the fact that light pollution inhibits star gazing. I am with you. There is absolutely nothing like looking at the stars on a moonless night in the mountains. It makes one really understand why the ancients had such a fascination with them. But, why do we need scientists to tell us that it is brighter in the city when there are clouds?

March 3, 2011 9:37 pm

This should be worthy of an IG-Nobel price, if they where no so serious.
Now if we turn of the lights but equip everyone with night vision goggles, would we save energy in the proces?

March 3, 2011 9:51 pm

Hey, this problem is real. The nearest dark sky location is now some 250 miles from my house, and my grandkids have yet to see a star filled sky, immediate action needed.
So here’s marching orders for the AGW camp:
Ditch the meaningless 0.0005 CO2 fraction campaign and shift all manpower and activists to this very real global problem. Lead by example this time, not with your mouths. Even my house has but one 24 watt bulb outdoors, so a great way to kick this off is to start at Al Gore’s flood lit white mansion. Just keep imagining all of that super-hot nighttime UHI air rising from those sodium-hologen lamps!
If you can’t even get your own Leader Gore to flip a frickn’ light switch, you might as well fold and go home.
( a win-win and at worse a return of some long lost stars )

Mike McMillan
March 3, 2011 9:54 pm

Ray says: March 3, 2011 at 4:31 pm
. . .That should be a good place to put a change a light bulb joke…
Q. How many climate scientists does it take to change a burnt light bulb?
A. None. The computer model says the light is not burned.

Okay, can’t resist.
Q. How many psychologists does it take to change a light bulb?
A. Only one, but it takes a long time, and the light bulb has to want to change.
But seriously,
This is much akin to our greenhouse effect, only with visible light so we get a feel for how much is happening. Light radiates upward, is absorbed, reflected, refracted around, and some goes on up to space and a small fraction is returned downward to repeat the process. Overall, things are a little brighter, as with greenhouse gasses making earth a little warmer.
A GISS computer model of this might show that if we increase the cloudiness at a given rate, we would find a tipping point where we get runaway light pollution and life on earth ends.
The glow in the Chicago image is like what Dr Spencer’s satellite sees in one of its IR bands. When flying at altitude at night above a low overcast (undercast for pilots), you can see the cities and highways connecting them. With higher clouds, the hot spots are more diffuse and harder to recognize.

Larry in Texas
March 3, 2011 10:07 pm

I remember when I was in San Antonio going to law school, around 1977-78. We had a major power blackout for about one or two hours across large parts of the city, and it was a very clear night when it happened. In the complete darkness, I was amazed – I had never seen so many stars in the sky before! It was the most awesome sight for me. All those years I was deprived by the city lights of this pleasant sight. And all the subsequent years since.
I wish we’d just turn off all the lights sometime, whether it’s cloudy or clear. Just to see all of the stars again.

March 3, 2011 10:16 pm

Turn off the streetlights! It only helps the bad guys see better as they go about their appointed rounds. If that would save 10% of our electricity waste, so much the better. As an astronomer, I can only be grateful that Tucson has some night illumination standards, however inadequate to the purpose. Good grief, people, aren’t we trying to make this a better world? This is a no-brainer.

March 3, 2011 10:25 pm

TomRude says:
March 3, 2011 at 8:31 pm
Outdoor lighting left on gives the criminal the ‘edge’ they need.
Real security takes place when motion trips the light and someone is paying attention.
Most crime occurs under the glare of outdoor lighting, as criminals are well aware that the lights are on, but nobody’s home.
The problem you have with security is that you expect a dumb device to take the place of safeguarding by a real person.
Even a silent alarm at a business is of no value unless someone responds quickly.

March 3, 2011 10:59 pm

Obviously we need to paint all our streets and parking lots bla… oh, wait… we just were told to paint them white.
OK – got it. We need to require all exterior light be directed horizontally. Horizontal, then, shall be the direction. Down shall not be the direction except that the direction shall proceed directly to horizontal. Up is right out.
And the people cheered and sang and prayed there be more. On to the ears of he who hears all prayer and every utterance fell these words and he heard. Moved by joy welling within his divine being he spoke unto the throngs there gathered and said – “I’m cool wi’ dat.” And across the land there ushered forth his ministers and magistrates of horizontal light and he saw it was good and said – “Yiminy, dots goot! Let der be dem der LIGHTS!”

March 3, 2011 11:38 pm

This will be used as an excuse for an energy saving campaign, lots of countries in the same boat as the UK with insufficient energy infrastructure planning.
For stating the bleeding obvious, this study ranks up there with that “animals feel pain like humans” study , but without the cruelty.

March 4, 2011 12:12 am

I live in a city where there are no working street lights, among many other things, and I can tell you driving in traffic without them is very difficult and scary. You can’t see road markings, the other guy on bright really makes it hard to see pedestrians, stopped cars, pot holes and so on.
I hate the light pollution but without it a city is somewhat unworkable. Fortunately I also enjoy astronomy so having been handed lemons I have made lemonade and don’t go driving after dark.

March 4, 2011 12:16 am

I live in Scandinavia at about 60 degrees North. Here we have “Light Pollution” all night long, every night in summer. Somehow humans (and everything else) have managed to survive this for thousands of years. As a matter of fact we love our “white nights”, it’s the dark days of winter when there is hardly any daylight at all that that are bad.

Carsten Arnholm
March 4, 2011 1:00 am

@tty March 4, 2011 at 12:16 am
Well, I live here too, and I am an amateur astronomer. The light pollution issue is a real problem and getting worse.
We only have short windows of real darkness in September/October and ~April if there is no snow on the ground and clear skies (which means almost never). In the summer season the natural light is too bright (given our location at 60N), but in the wintertime when it should be real dark it isn’t, due to reflection of high power artifical lights in the snow and atmosphere. Often you can’t see many stars at all.
Recently, a local football field was given new lights about 2km from where I live and ~120m below me, behind a hill. It still ruins the whole eastern sky with a giant “reflection column” that can be seen even from inside my house when the indoor lights are on.

Charles P
March 4, 2011 1:53 am

The issue of light pollution (or whatever you call it) seems to have drawn out some very divergent views here.
As an amateur astonomer, living in a city, I expect the night sky to be lighter than if I lived in the middle of nowhere. I don’t expect all lights to be turned off, and I don’t think that this is what dark sky campaigners are asking for.
What I object to is lighting that makes the situation worse for no apparent benefit. Examples are things like lighting church steeples, advertising hoardings brightly lit all night. The other main culprit is poorly directed/shielded street lights. Having my bedroom illuminated by the light outside does not protect me from robbery, mugging or rape, nor does it stop my car being broken into. All it does is waste money.

John Marshall
March 4, 2011 1:58 am

More alarmist rubbish. Light pollution is only a problem if you wish to see the stars but with 8/8 cloud cover it does not matter where you are they are hidden.

March 4, 2011 2:52 am

First off – I’m a photographer. I really like astrophotography and spent a lot of money and effort learning that very difficult craft. So there is my bias, up front. Until recently, I did all my astrophotography from my backyard. Some of the equipment:
You can see some of the work I’ve done out of my back yard below – some of it requiring two and three nights of exposure:
Sadly, with the real estate explosion that came at the beginning of this century I am no longer able to do those images from my backyard unless there is very low humidity in the air – a very rare thing here in Florida. The additional thousands of lights now in my neighborhood overpower the faint signal to noise ratio of these very dim sky objects. Colors are also completely distorted because a lot of the lights have a very narrow spectrum. It’s not the lights really, it’s the design of the lights. Most light fixtures throw 30 percent or more of their light upwards, where it’s not needed at all.
And yes, lighting the night and feeling safe because if it is in our DNA. No problems there. I just wish it wasn’t pointed where it is not needed. We humans have reasonably good night vision. With dark adapted eyes we can see really well after Sunset. The problem is that we light the inside of our homes so well that when we step outside our eyes are not adapted and we are basically blind. So, we use a lot more light outside than we really need because of this adaptation problem. I see no solution to the problem so I just don’t do much astrophotography anymore, and all that equipment has now become very expensive living room adornments – sigh.

Bloke down the pub
March 4, 2011 3:24 am

I recently took up astronomy but was bugged by a street light. After a phone call to my county council highways department a nice man came and painted black the side of the lamp that faced my property. Not a complete solution but a vast improvement that was cheap and efficient. There is some common sense to be found in local government.

March 4, 2011 3:52 am

Dr. Dave says (3/3/11 at 8:52pm): …”On a moonless night it’s darker than the inside of your hat. I received a notice from a law firm that alerted me that I was to immediately remove the flood lamps mounted on my garage.”….. “This is personal to me because a few months later I was taking my recycling out to the street in the pitch dark, tripped, fell and broke a rib. I remember laying on my back that cold November night thinking “Gee…the night sky sure is beautiful!”.”
The joys local politics! If you happen to have a relative who is an attorney you might find it kind of fun to sue the city for your medical bill- i.e. the rib. I leave my spot lights on all night long (CFL’s to save energy). I love your approach to the problem (find a way around the rules) by the way. The bright lights on my truck have come in handy a few times when we have lost power- to light the path between our buildings.
We have some rule out here in the foothills of CA on how loud your generator can be…………. I’ll bet you are going to have a similar law soon too.

March 4, 2011 4:27 am

Extremely simple means to reduce night-sky pollution & still maintain ground illumination. Construct the outdoor lights to have their horizontal bottoms illuminated only (no light emitted sideways). Boxy looking, but much more efficient & light pollution is greatly reduced.

Greg Holmes
March 4, 2011 5:06 am

Light pollution is a problem for astonomers, and it is real. The media in the UK looked at this topic a couple of years ago. Streetlights for example should light the streets, cannot fault the logic. If we are wasting 30% of their oputput, shining up at the clouds we are nuts, why is there not a correct design of streetlight? more light where it is needed, less power required? less cost? am I wrong?

amicus curiae
March 4, 2011 5:11 am

LED street lighting is available and lights only the areas needed, I think it was a smart councillor in Hawaii a few years back? replaced the towns lights with leds, he saved the council millions in power bills and replacing the burnt out bulbs, and sure would have reduced the “pollution” of the night skies as a bonus.
where I lie in Aus as above stated by others at night in rural areas we get magnificent starry nights, you really do feel you can reach up and touch.
you can also get very lost, fall and injure yourself with little effort, a torch isnt a toy its a necessity.

March 4, 2011 6:17 am

Blimey, there short-thinkers here. Leaving aside the question of who funded the research (and the one about whether or not the researchers are trying to jump on a gravy train… ’cause that would be a first, wouldn’t it?), let’s go through a few points, from the point of view of someone who grew up in London, then the Sussex countryside in England, and has since lived both in major cities and the pitch-black countryside:
1. Streetlights are still necessary for roads, even with every vehicle having headlights (assuming the fine, upstanding occupant remembers to turn them on), as the major problem with unlit roads are high-contrast shadows cast by the vehicle’s headlights, and glare from other headlights. Stuff can hide in shadows… like people, animals, stone walls, precipitous drops, etc. Good lighting can reduce the contrast to the point where the average human eye’s dynamic range is sufficient to extract detail from the shadowed areas.
2. There are no studies (and there have been a few, and no, I’m not going to cite them here, as it’s still early – Google is your friend here) that show positive correlation between higher illumination levels and reduced crime levels. Streetlights and other high-output lighting (so-called “security” lights) make people feel safer, but that’s about it. In fact, what they really do is provide deep shadows for the naughty people to hide in… see point 1 above (and ask me how I know after years of living in brightly-lit cities). The converse is that in the pitch-black country night, you learn to carry a torch, for crying out loud! That’s just common sense. It also means that naughty people would have to do the same, unless they’re wearing night-vision gear, making them stick out like a sore thumb.
3. “Natural” light pollution… oh, come on! In Scotland (where my family is from), you can read a newspaper by the light of the night sky in the summer. The closer you get to the poles, the more light there is during the summer months. Fact of life. This does not equate to the twerp next door deciding he’s going to mount a 500 watt “security light” on the side of his house, set in such a way that you never actually need to turn on the lights inside your own house. If I lived in Scandinavia, my circadian rhythms would adjust (just the same as they do after flying over a few time zones), but they can’t adjust to Dave next door turning on the light when he feels like it. Nor should they have to.
4. Final point: look at the photo of Chicago above. If you’ve complained about the funding for the study, realise this – these are your tax dollars/pounds/Euros being wasted. Simple as that. It’s got nothing to do with “warming the planet” or other such tripe. It’s just waste. You don’t leave the engine running when you’ve parked the car, or drive in the lowest gear possible, or leave the ‘fridge door open, or the water running, because these all cost you money. Why does anybody in their right mind thinks it’s OK to throw away two-thirds of a paid-for service?
Sorry if any of you feel ‘trivialised’ in any way by this. Actually, no I’m not. This is an issue by and of itself, and frankly some of the arguments here have been laughably juvenile, and do not do justice to the generally higher tone of comments this site usually enjoys.

March 4, 2011 7:13 am

It’s really bad when there’s snow on the ground. Frightening!

March 4, 2011 7:55 am

I think, this is not the point of Anthony’s article.
Tim Ball says:
March 3, 2011 at 3:46 pm
What does this do to Hansen’s night-light brightness measure of the urban heat island effect?

It’s more about this salient point!
Higher light “pollution” could be a reason for increased GISS data.
As they’ve abandoned rural stations, the urban stations show more light and therefore
interprets to higher temperature.
We should discuss THIS theme.

C.M. Carmichael
March 4, 2011 8:38 am

There is an easy way to darken the night sky, rely on sun and wind for power.

Patrick Kelly
March 4, 2011 9:37 am

I could have told them that, on overcast nights, the clouds reflect the artificial light making it brighter in my suburb. Where to I send for my funding cheque?

Jeff C.
March 4, 2011 11:11 am

Following up on Bloke down the pub’s comment, we had a very similar experience.
We bought our dream house with large gable windows across the front. It was not until our first night in the house that we realized the streetlight in front of our house shined through the windows all night long. I called the city maintenance department and they immediately retrofitted the streetlight with a conical shroud that completely eliminated the problem. The previous owners had just lived with the problem for twenty years.
Most of the older streetlights were poorly designed and didn’t constrain light to a downward direction. This is easily rectified in most cases.
As for those saying this is a serious problem, get a grip. Malaria in Africa, narco-terrorism in Mexico, and the US budget deficit are serious problems. This is an annoyance. Just because it bothers you doesn’t make it a problem for the rest of us.

March 4, 2011 11:22 am

Ref – Creepy says:
March 4, 2011 at 7:55 am
You’re on! This is one of a number of problems with Hansen, et al; the science really isn’t very settled at all. Noise pollution is another problem with Hansen that hasn’t “hit the fan” yet.

March 4, 2011 9:54 pm

What a beautiful photo! Absolutely incredible! Congrats for bringing this to attention.

Allan M
March 5, 2011 2:57 am

“…the amplification of light pollution by clouds is large, and should be taken into account.”
The clouds do not amplify, they reflect. So these nerks can’t even think straight. It did say “physicists and ecologists.” Maybe (optimistically) the physicists didn’t write the report. No wonder the talk about positive feedbacks from water vapour.

March 5, 2011 8:49 am

– The post says “We found that overcast skies were almost three times brighter than clear at our rural location, and ten times as bright within the city itself,”
The impact of reflection from the same cloud bank was an amplification over the clear sky luminance of either a factor 3 or 10, depending on where it was measured. It’s not like clouds in the city can reflect three times as much light…
Also, regarding why light pollution sucks, even if you don’t like to look at stars – light pollution is suspected to cause health problems, by screwing up melatonin production:
or here: “We found a significant positive association between population exposure to light at night and incidence rates of prostate cancer, but no such association with lung cancer or colon cancer.” Read More:
There is also new evidence from mice that suggests light pollution might also be a factor behind the obesity epidemic.

Tim Clark
March 5, 2011 10:22 am

This is truly a “duh” revelation.

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