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What are the mysterious light sources on light pollution maps?

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Re: What are the mysterious light sources on light pollution maps?

#81

Post by myself248 »

paulmd wrote: post #77
vvanders wrote: post #62

Earlier quoted context omitted.

They also tend to generate a ton of RF noise if not properly filtered.

I was having problems with my cable internet periodically dropping out for a few minutes at a time, it took them two or three tries, and every time the support guy came out they were very careful to tell me that "your neighbors grow lights may cause that when they switch on at some particular time every night". So I guess they do put out quite a bit of RF noise ;) ("of course, it's company policy never to imply owner…

Grow lights are pretty notorious.

http://www.arrl.org/grow-light-rfi

"even under the best of circumstances, the importance of diplomacy cannot be overemphasized during these discussions"

Re: What are the mysterious light sources on light pollution maps?

#82

Post by Someone »

GekkePrutser wrote: post #31
bzbz wrote: post #23

Earlier quoted context omitted.

Take them off during the daytime. They're not permanent installments.

Those greenhouses are the size of many football fields.. Putting tarps over them is a job that will take many days :) But yeah shutters or something smarter (like two-state glass) should work IMO. I think you even get glass that can switch to mirror mode.

There is research on whether solar arrays would be a net benefit. Those cells would catch most of the sun’s light, turn it into electricity to power the LEDs that have wave lengths that are better matched to what the plants need.

A variation of that only catches the sun’s green light and uses it to power pink/red LEDs (https://www.treehugger.com/solar-technology/solar-smart-gree...)

Re: What are the mysterious light sources on light pollution maps?

#83

Post by Neeek »

reaperducer wrote: post #40
paulie_a wrote: post #32

Earlier quoted context omitted.

Did Chicago figure out the issue with LEDs and snow. The old lights melted snow, the LED lights did not

The LED and snow issue is about traffic lights, which are horizontal and therefore subject to getting filled with blowing snow. Streetlights face down and don't have a cavity to fill with snow.

It's also FUD, it's trivial to add a heater to the LEDs and still come in at a lower wattage than a tradition lamp.

Re: What are the mysterious light sources on light pollution maps?

#85

Post by abrowne »

paulie_a wrote: post #32
3JPLW wrote: post #13

Earlier quoted context omitted.

Chicago has been slowly replacing its yellow sodium streetlamps with efficient LEDs that project down instead of up. They've been working block-by-block in a systematic way that you can see when you fly into the city at night. It's quite dramatic.

Did Chicago figure out the issue with LEDs and snow. The old lights melted snow, the LED lights did not

We've been getting LED street lights in Minneapolis, so can't be a problem now.

Re: What are the mysterious light sources on light pollution maps?

#86

Post by onychomys »

krick wrote: post #29
deathanatos wrote: post #26

> Kiluaea (sic?), as an active volcano, regularly has literal glowing lava occupying the caldera. Not anymore, sadly: https://www.nps.gov/havo/planyourvisit/lava2.htm > Beginning in May, 2018, the lava lake that existed inside Halema‘uma‘u crater disappeared and lava flows from Puʻu ʻŌʻō crater have ceased. There is no molten lava or lava glow to see anywhere in or out of the park. (I would still recommend visiting:…

I wonder if there are some other places in the world I could visit reasonably expecting to see molten lava and all that dramatic looking stuff.

There are currently seven permanent lava lakes: https://en.wikipedia.org/wiki/Lava_lake

Re: What are the mysterious light sources on light pollution maps?

#88

Post by brownbat »

amatecha wrote: post #8

Ah yeah, in the post's first "unknown light pollution" example, I figured it must be a greenhouse. I was driving through a relatively small town one time and was a bit freaked out by this ominous yellow glow off in the distance. Like, the whole sky was glowing [0]. I ended up driving out to try to find the source, and discovered it was a huge greenhouse/farm. Luckily not an extraterrestrial landing zone or so on ;) […

These greenhouses and all the complicated local politics that go along with them are the subject of a great episode of Outside/In:

http://outsideinradio.org/shows/ep45

Re: What are the mysterious light sources on light pollution maps?

#89

Post by astura »

maxerickson wrote: post #67
3JPLW wrote: post #13

Earlier quoted context omitted.

Chicago has been slowly replacing its yellow sodium streetlamps with efficient LEDs that project down instead of up. They've been working block-by-block in a systematic way that you can see when you fly into the city at night. It's quite dramatic.

My town replaced the sodium light across the street with a LED. A lot more light comes in the windows now. It sucks.

You can't use blackout curtains?
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