Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

US Streetlights Are Turning Purple

scientificamerican.com

Post reply on HN
Print view View original

91–100 of 122 posts

Re: US Streetlights Are Turning Purple

#91

Post by mcv »

kuon wrote: post #87

It is not directly related to the article, but the decaying LEDs mentionned in the article made me think of it. Since we had to switch to LEDs, I had to change lightbulbs waaay more often. I realize they consume less (even if here they would just help heat the house so the energy is not lost), but hell they are crap. They start blinking, their color is shifting, they die quickly, they are super expensive, they are bi…

Good leds are extremely durable and should last far longer than anything else, but it seems like there are also a lot of crappy leds on the market.

But it's also important that leds receive the right amount of power. If they receive too much, they'll burn out. We've had this issue with a system where you clip little lights on a rail. It uses GU10 spots which exist in led, so thinking that was compatible, I used leds of course. But our spots kept burning out at an alarming rate. Turns out we need a different transformer for leds. I'm using halogen now, and it works fine.

Re: US Streetlights Are Turning Purple

#93

Post by [deleted] »

metalman wrote: post #52
robertlagrant wrote: post #35

Earlier quoted context omitted.

Yes but that's the point: sodium vapour offers worse peripheral vision, so it could make some situations riskier.

no way, once something is into your periferal vision while in a moving car it's too late, and fact does not matter....unless it's moving realy realy fast, and then it's still too late so the real equation will involve all sorts of other inputs, like the coulor temp, and amount of direct vs reflected light, background light conditions, weather, and indivual perception of any given driver. *green light is the worst, as…

[deleted]

Re: US Streetlights Are Turning Purple

#94

Post by supermatt »

metalman wrote: post #52
robertlagrant wrote: post #35

Earlier quoted context omitted.

Yes but that's the point: sodium vapour offers worse peripheral vision, so it could make some situations riskier.

no way, once something is into your periferal vision while in a moving car it's too late, and fact does not matter....unless it's moving realy realy fast, and then it's still too late so the real equation will involve all sorts of other inputs, like the coulor temp, and amount of direct vs reflected light, background light conditions, weather, and indivual perception of any given driver. *green light is the worst, as…

[flagged]

Re: US Streetlights Are Turning Purple

#95

Post by aitchnyu »

userbinator wrote: post #88
kuon wrote: post #87

It is not directly related to the article, but the decaying LEDs mentionned in the article made me think of it. Since we had to switch to LEDs, I had to change lightbulbs waaay more often. I realize they consume less (even if here they would just help heat the house so the energy is not lost), but hell they are crap. They start blinking, their color is shifting, they die quickly, they are super expensive, they are bi…

Phoebus Cartel 2.0

Seems the elements are warrantied for 10000 hours but the drivers are not.

Re: US Streetlights Are Turning Purple

#96

Post by adrian_b »

kuon wrote: post #87

It is not directly related to the article, but the decaying LEDs mentionned in the article made me think of it. Since we had to switch to LEDs, I had to change lightbulbs waaay more often. I realize they consume less (even if here they would just help heat the house so the energy is not lost), but hell they are crap. They start blinking, their color is shifting, they die quickly, they are super expensive, they are bi…

There are plenty of cheap LED lamps with inadequate cooling or other bad components, which will become defective after a relatively short time.

I have switched all the lighting in 2 apartments to LED lamps, more than 10 years ago, and no lamp has gone defective until now.

However, they were Philips lamps and not one of their cheapest models, but some model with 1521 lumen @ 13 W and 4000 K color temperature, i.e. slightly more luminous than the classic 100 W incandescent lamps and with almost white light, only very slightly yellowish, very unlike the yellow lamps with a color temperature under 3000 K, and also very unlike the cheap bluish lamps with a 6500 K color temperature.

My LED lamps are screwed in traditional incandescent lamp fixtures, which hang from the ceiling, but unlike some bad lamp fixtures, mine have below them a diffusive screen, to avoid direct light, but they are completely open above, so they do not impede cooling.

Re: US Streetlights Are Turning Purple

#97

Post by adrian_b »

hedora wrote: post #16
BorgHunter wrote: post #8

Earlier quoted context omitted.

It depends strongly on implementation. LEDs can produce white light at any color temperature and CRIs ranging from terrible to great. Quality LEDs are quite nice indeed (when they're not turning purple). Most LED streetlights replaced sodium vapor lights, though, which produce the sickliest, most horrible orange color known to humanity. Just about any LED is an improvement over those.

Sodium lights aren’t even orange in the normal sense of the word. They only emit one wavelength.

There are 2 kinds of sodium lamps.

Low-pressure sodium lamps emit a single wavelength and they are the only kind of lamp that does not use LEDs, but which can match or exceed the energy efficiency of LED lamps. However, with low-pressure sodium lamps you cannot perceive any color.

There are also high-pressure sodium lamps. They emit a broad-spectrum light, even if with an excess of orange-yellow light. You can perceive the colors of things with such lamps, even if not very well. However the high-pressure sodium lamps have a much lower energy efficiency than LED lamps.

In Europe I have encountered mostly, or perhaps only, high-pressure LED lamps used for public lighting. I have used at home some low-pressure sodium lamps for certain purposes, but I am not sure if I have ever seen one like that used in a public space, here in Europe.

Low-pressure sodium lamps typically use transparent glass bulbs, like incandescent lamps or any other kind of low-pressure gas-discharge lamps, e.g. neon lamps.

High-pressure sodium lamps use special bulbs made of translucent alumina ceramic, because glass would not survive in those conditions.

Re: US Streetlights Are Turning Purple

#98

Post by adrian_b »

lukas099 wrote: post #49
looofooo0 wrote: post #32

Earlier quoted context omitted.

What is the normal sense of the word? I only know the CIE standard observer to define colour and with this it is clearly in the equivalence class of orange.

I think they mean they don't emit a "natural" orange (like an orange flower) that is really some kind of sum of many wavelengths. I could be wrong though.

A pure orange contains only light with a single wavelength.

A mixture of light with different wavelengths that is perceived as orange cannot be distinguished from a mixture of some pure orange with a certain amount of white light.

So any orange, of a flower or of anything else, has the hue of a single wavelength, but it may be more or less saturated, appearing like light with a single wavelength mixed with some white light.

Low-pressure sodium lamps emit a pure color that belongs to the yellow-orange range, so you could describe it as a yellowish orange.

High-pressure sodium lamps have a desaturated orange color, i.e. light that looks like a mixture of orange and white lights.

The orange of any kind of sodium lamp is much more yellowish than the reddish orange of neon lamps with cathodic light, like those used in neon indicators.

Most sodium lamps contain some neon for starting, so when they are switched on they may emit a reddish orange light for a short time, then change to a yellowish orange light, when the sodium vapor takes over from neon.

Re: US Streetlights Are Turning Purple

#99

Post by ssl-3 »

neutronicus wrote: post #20
joshstrange wrote: post #14

> And yet some streetlights have suddenly turned a jarring shade of purple. It is hard to determine the exact cause without dissecting one of the defective lights, but scientists have a hypothesis: bright purple light suggests the phosphor layer around the lights has been “delaminated”—peeled off—exposing the blue LED light underneath, Brgoch says. What an annoying/bad article. "Here are our guesses of this when we c…

FWIW I do wear sunglasses for long highway drives at night. Without them halogen headlights in my side mirrors give me a migraine after a while.

Are you sure you mean "halogen"? *

Halogen headlights have been the most common (and relatively cheap!) kind on the road for many decades. They're just like the tungsten filament incandescent space heaters we used to use at home, except they burn at a somewhat higher color temperature. (And the way they work is really really neat, but I digress.)

Halogens, while higher-temperature than regular tungsten headlights (which haven't really been used at all in many decades) are generally "yellow"-ish compared to modern HID (aka "xenon" or "metal halide") or LED headlights.

Anyway, I'm also bothered by lights when driving at night, and I find the yellower corner of the spectrum to be the least-bothersome of common lighting colors. The glaring ~6000k white of modern HID and LED is much worse, for me, apparently because of the extra blue spectrum.

But if it really is yellow-ish halogen lights in your side mirrors that bother you most*, then I can't tell you that you're wrong.

And if that is then case, I can potentially offer some constructive advice: I've owned a couple of cars (specifically, a 4th gen Firebird and an E36 BMW -- both products of the middle 1990s) that came from the factory with side mirror glass that was tinted a pale blue.

The slightly-blue tint attenuated yellow halogen lights, by design. It's a clever bit of optical filtering.

During the day, in the sun where there's tons of light, they worked mostly-normally: Reflected images had little bit of blue tinge, but whatever.

And at night, the halogen headlights that were nearly-ubiquitous in the 1990s had their reflected intensity turned down automatically. Compared to cars with mirrors that used clear glass, I could still see the lights of the cars behind me just fine. They were simply less-blinding.

It worked great around the times those cars were produced.

If that's really the problem you're experiencing*, then a very pale blue window tint on the mirrors may be exactly what you want for that issue.

* (I asked for specificity because it's important. That Firebird and E36 both became increasingly-annoying for me to drive at night as HID and LED lights became increasingly-common, and towards the end of my time driving them I was seriously considering having clear glass mirrors cut and swapping over to that. Not because the blue tint wasn't effective at filtering out halogen light (it was great at that!), but because it seemed to magnify the problems I experience with HID and LED headlights. The world was changing, and the unchanged spectral filtering became a burden instead of a boon.)

Post reply on HN