3 ms·

The headline suggests that people have seen treetops glowing and it just hasn’t been captured on video before. The actual pictures and video is of something tha

The headline suggests that people have seen treetops glowing and it just hasn’t been captured on video before. The actual pictures and video is of something that nobody could have seen with their eyes.

WarmWash 6mo ago
You can absolutely see corona discharge like that with your eyes. If you come to my day job, and we shut off all the lights in the test room, after your eyes adjust in the dark for a minute, you'll see the soft purple glow coming from the edge our 160kV test rig. Definitely emits UV, but there is enough visible to see it for sure. It comes from the electrons exciting nitrogen in the air.[1] 1. https://commons.wikimedia.org/wiki/File:Nitrogen_discharge_tube.jpg https://commons.wikimedia.org/wiki/File:Nitrogen_discharge_t...
- ajkjk 6mo ago
  what's the job?
- yetihehe 6mo ago
  > (1:If you come to my day job), and (2: we shut off all the lights) (3:in the test room), (4:after your eyes adjust in the dark for a minute), you'll see the soft purple glow coming (5:from the edge our 160kV test rig). So, 5 different things that make it glow "not coming from treetops". Parent poster wanted to see glowing treetops in a forest, where we might not be adjusted to dark for a minute. You can also see such corona discharge with benchtop tesla coils even in lighted room, but those are not trees in forest glowing from a storm.
  - MisterTea 6mo ago
    Even a smallish Tesla coil easily produces voltages north of 160kV. I built one using 4" PVC for the secondary with a wound length of maybe ~2 feet of secondary? From memory of the calculations I did at the time I think it was around 350 kV peak? Might have been higher. Threw 24 inch sparks quite easily.
- clickety_clack 6mo ago
  I’m not saying it can’t be seen, I’m saying that you can’t prove something can be seen by showing me a photo that captures light that I can’t see.
eel 6mo ago
This reminds me of a chat room interaction I had maybe 25 years ago. The other person was adamant that humans can't see the infrared from TV remotes, and I was adamant that I could. It was pretty a widespread belief (even in school science books) at that time that humans couldn't see infrared. Since then more science was done to prove that, in fact, some humans can see some infrared under some conditions. I share that mainly to state that humans are amazing and have a wide and inconsistent range of capabilities (and sometimes even mutating into new capabilities!) Personally, I will always hesitate to say "nobody" and I lean towards "no typical human" instead. :)
- lukan 6mo ago
  I suppose this also depends on the types of remote controls? There are some where I can see red and some where I cannot.
  - MisterTea 6mo ago
    The faint red glow is actual red light as many IR LED's (esp the ones used in cameras for night illumination) are close to the visible spectrum and have some visible light emission.
    - formerly_proven 6mo ago
      850nm is easily visible, but most remotes are 940nm, which is also visible as a faint purple glow but the source needs to be really bright.
- dtgriscom 6mo ago
  Isn't infrared, by definition, wavelengths beyond what people can see?
  - jibal 6mo ago
    Which people? And no, it's not defined that way: "radiation having a wavelength between about 700 nanometers and 1 millimeter"

WarmWash 6mo ago

You can absolutely see corona discharge like that with your eyes. If you come to my day job, and we shut off all the lights in the test room, after your eyes adjust in the dark for a minute, you'll see the soft purple glow coming from the edge our 160kV test rig. Definitely emits UV, but there is enough visible to see it for sure. It comes from the electrons exciting nitrogen in the air.[1] 1. https://commons.wikimedia.org/wiki/File:Nitrogen_discharge_tube.jpg https://commons.wikimedia.org/wiki/File:Nitrogen_discharge_t...

ajkjk 6mo ago
what's the job?
yetihehe 6mo ago
> (1:If you come to my day job), and (2: we shut off all the lights) (3:in the test room), (4:after your eyes adjust in the dark for a minute), you'll see the soft purple glow coming (5:from the edge our 160kV test rig). So, 5 different things that make it glow "not coming from treetops". Parent poster wanted to see glowing treetops in a forest, where we might not be adjusted to dark for a minute. You can also see such corona discharge with benchtop tesla coils even in lighted room, but those are not trees in forest glowing from a storm.
- MisterTea 6mo ago
  Even a smallish Tesla coil easily produces voltages north of 160kV. I built one using 4" PVC for the secondary with a wound length of maybe ~2 feet of secondary? From memory of the calculations I did at the time I think it was around 350 kV peak? Might have been higher. Threw 24 inch sparks quite easily.
clickety_clack 6mo ago
I’m not saying it can’t be seen, I’m saying that you can’t prove something can be seen by showing me a photo that captures light that I can’t see.

eel 6mo ago

This reminds me of a chat room interaction I had maybe 25 years ago. The other person was adamant that humans can't see the infrared from TV remotes, and I was adamant that I could. It was pretty a widespread belief (even in school science books) at that time that humans couldn't see infrared. Since then more science was done to prove that, in fact, some humans can see some infrared under some conditions. I share that mainly to state that humans are amazing and have a wide and inconsistent range of capabilities (and sometimes even mutating into new capabilities!) Personally, I will always hesitate to say "nobody" and I lean towards "no typical human" instead. :)

lukan 6mo ago
I suppose this also depends on the types of remote controls? There are some where I can see red and some where I cannot.
- MisterTea 6mo ago
  The faint red glow is actual red light as many IR LED's (esp the ones used in cameras for night illumination) are close to the visible spectrum and have some visible light emission.
  - formerly_proven 6mo ago
    850nm is easily visible, but most remotes are 940nm, which is also visible as a faint purple glow but the source needs to be really bright.
dtgriscom 6mo ago
Isn't infrared, by definition, wavelengths beyond what people can see?
- jibal 6mo ago
  Which people? And no, it's not defined that way: "radiation having a wavelength between about 700 nanometers and 1 millimeter"