Lights On, Lights Off

You can learn a lot from satellite pictures of the earth at night; the famous picture of North and South Korea, which Tyler and I feature in Modern Principles, is just one such example.

ESRI has an interesting picture-story illustrating the lights that have turned on and those that have turned off between 2012 and 2016. It’s remarkable how much North India literally turns on in this short space of time. Lights have also turned off around the globe. Not only in places like Syria but also in much of the United States and Northern Europe. In the latter two cases, as the surprising result of more efficient lighting and campaigns to reduce light pollution. Check it out.

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While there is outer darkness in America's so-called shinning city on a hill, it is morning in Brazil. Brazil's stock market is the of the greatest of tge workd.

Why is Brazil so dark? Does the government cut off the power at night ? It doesn't look much brighter than Africa and substantially darker than India ?

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'In the latter two cases, as the surprising result of more efficient lighting and campaigns to reduce light pollution.'

There is nothing surprising when more efficient lighting and campaigns to reduce unnecessary light at night result in exactly what they were intended to produce.

Oh?

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Au bloody contraire, it is a source of wonder when campaigns result in exactly what they were intended to produce.

Efficiency is fairly easily measured, and generally an advantage to take advantage of, certainly over the longer term.

Talk to anyone running a truck fleet - efficiency represents saved money, and they have no problems implementing efficiency programs - if only to keep up with their competition.

I think it was more a comment on government inefficiency.

Of course it was - yet government does not need to mandate savings on lighting costs when the market provides for it through modern lighting systems being both cheaper to run and having longer lifespans at a lower cost.

Generally, only the complacent don't actually continue to invest in efficiency.

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I think clockwork_prior has the better argument here. Lighting efficiency is driven by economic efficiencies. So absent market distortions, one should expect that the light shining into space to be a waste product and that efficient users would reduce it over time.

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"Check it out." Don't you give me peremptory instructions like that, young man.

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I'm not crazy about the pink/blue method of trying to show lights off/on, vs. just showing me two maps and letting me quickly navigate between them. The latter feels more real, like I'm looking at real imagery, which hopefully I am. The former is just like a graph somebody put together, which is interesting, but not "Oh COOL" like looking at an actual satellite photo.

Another mapper has done a map with a slider so you can toggle between 2012 and 2016:

http://www.digital-geography.com/wp-content/uploads/2017/04/index2.html#7/29.554/-98.871

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Energy efficient lighting almost always means more lumens per watt, i.e. replacing a 60 watt incandecant bulb with a 9 watt LED - but the amount of light (lumens) produced is, by design, the same. So I woudn't expect "energy efficient" lights to have much visible effect.

There is some effort to push more directional (usually down) fixtures for public lighting like street lights, to get more ground usuable light.

And there is some effort to adopt lighting with a more astronomy friendly spectra. I didn't see spectra shift discussed in article.

When I worked at IBM Almaden Research Center, they had special lighting precisely to avoid interference with astronomical observation. The lab is on top of a mountain, and I believe that made it more visible to the Lick Observatory on top of Mt. Hamilton, even though there's quite a distance between the two.

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@Engineer - yes I didn't understand the point about more efficient lighting meaning less light. If anything, more efficient lighting should mean more light, since it is now cheaper. The lights off areas seem to be areas that have more depressed economies in recent times - southern Europe, the US rust belt, South Africa.

I doubt very much that the astronomical protection effect is very large.

2012 to 2016 probably shows a shift towards low pressure sodium-vapour street lamps that give off longer wavelength light that interferes less with night vision then "whiter" lights. So this is an energy efficiency measure that has made cities less bright. This trend may change now shorter wavelength LED street lights are becoming popular.

In some locations street lights are switched off reduced late at night as an efficiency measure. I don't know if this practice has increased or not since 2012.

A NASA earth scientist weighed in over at Nat. Geo

"Maps like these are good for highlighting qualitative change. But to really study the change, Román says the best thing to do is look at the magnitude of the change of each pixel, measured in radiances, which takes into account things like viewing angle."

https://news.nationalgeographic.com/2017/04/satellite-imagery-night-earth-lights/

My googled conclusion: the mapmaker has done a great service; it's not his fault that interpretation is proving hard.

"My googled conclusion: the mapmaker has done a great service; it’s not his fault that interpretation is proving hard."

Yes, the very first interpretation of a complex problem is very seldom correct.

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Looks like South Africa is dimming significantly. I wonder why (and why it wasn't mentioned)?

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It also isn't mentioned that Russia has brightened. This is not readily apparent, as the city centers in Russia are separated by large swaths of lightly developed towns and villages - which likely have not seen much in the way of improvement. However, it is significant for the geopolitical environment if the cities have continued to improve. One could possible infer from this that the well-being of the middle class in Russia has continued to improve, overall. If that is the case, then internal support for Putin's regime will remain strong.

I would also discount the impact of lighting campaigns in North America. The results are too varied to make such a conclusion without a great deal more data.

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I appreciate the link, but also found it confusing. The western ring around DFW, and the southern part of the ring around Houston, turned pink. And all the sprawl around Austin. I know nobody turned off any lights - quite the reverse - and I don't think that any car dealerships went out of business. LED lightbulbs have come on strong, but Engineer points out they are not actually dimmer. It's hard to imagine that so many suburban fixtures changed from illuminating the sky to pointing at the ground, but not in the central city? I mean, I'm happy there is dimming going on ... I'd be even happier if I owned some mineral rights around - if I'm reading the map right - Pecos, Texas.

Hoping some bright bulb can illuminate further.

I wonder if this is also capturing car headlights? In recent times there have been many new changes in headlight technologies, which have probably changed the spectrum of the lights. This might be recorded as a drop.

Maybe so - but again counterintuitive, since those new headlights *seem* if anything brighter and more blinding.

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LEDs direct all of their light in one direction, because the LED chip is flat and only emits from one side. (The emission pattern is essentially a cone.) Incandescent and fluorescent lights emit light in pretty much all directions, except through the base or a reflector if it's got one. Because LEDs are inherently directional, it makes sense that you'd direct light toward only what you'd like to illuminate.

This is similar to the energy efficiency increase we've seen in the cellphone network. There were plans to use the cell network for drone delivery navigation. Nope. The newest transmitters don't waste energy transmitting into outer space. Unless your drone is flying below the towers, there's no signal for it to use.

Oh, interesting. Thanks.

Well, another question. Incandescent bulbs came in a range of brightnesses, from 15W on up (I know watts don't measure brightness, but you know ...) LEDs don't seem to come in this variety. Wishing to replace some old eyeball fixtures in my house, I ended up just getting better-looking baffles and continued using bulbs of various kinds, even though I know newer houses all have those those integral LED canlights that last forever. Partly because in looking it up on the internet, many people seemed to be focussed on putting a dimmer at the switch to permanently dim the LEDs, which are too bright.

Why do they have to be so darn bright? Do they make a ton of light at even the smallest wattages or something?

Does everyone else like them? I have a few but I don't want them all over.

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If you want to get into the weeds on lights and astronomy, see

http://physicstoday.scitation.org/doi/10.1063/1.3273014?journalCode=pto

Short version: outdoor lighting is their problem, the intensity of outdoor lighting (parking lots, gas stations, etc.) is going up, think 10X. The astronomers are fighting a delaying action (via output spectrum regulation and fixture design), but losing to population encroachment.

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While no doubt too dim to show up on this map, I would expect many off-grid areas to have gotten brighter thanks to the spread of solar lights using efficient LEDs.

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More academic nonsense.

Without a doubt. Space is black, so clearly its blackness would absorb light from cities at night before it could reach satellites, rendering it impossible to take photos of them at night.

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Good news for India and Iraq, not so much for Syria?

Very cool, Alex. Thanks.

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