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Ultraviolet corona discharges on treetops during storms

psu.edu

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Re: Ultraviolet corona discharges on treetops during storms

#61

Post by jibal »

dtgriscom wrote: post #54
eel wrote: post #32

Earlier quoted context omitted.

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 tha…

Isn't infrared, by definition, wavelengths beyond what people can see?

Which people? And no, it's not defined that way: "radiation having a wavelength between about 700 nanometers and 1 millimeter"

Re: Ultraviolet corona discharges on treetops during storms

#63

Post by colanderman »

raincole wrote: post #27
colanderman wrote: post #3

There is in fact no photograph of treetops glowing. There is a digital UV-wavelength video of the corona, and a visible-wavelength video of the trees. The paper [1] contains a sole picture with tiny circles indicating where the UV-video detected corona events, overlaid over a frame of the visible-wavelength video. The paper does also contain a video [2] which overlays a somewhat processed version of the UV video over…

That's some weird semantic nitpicking. Wikimedia has a category of "photographs of the Sun": https://commons.wikimedia.org/wiki/Category:Photographs_of_t... Do you think they are not photographs of the Sun because these are not what I see if I look at the sun with my eyes? (In which case I'll see pure white then perma black, I assume.)

Can you point me to the images of corona in the paper which I missed?

Re: Ultraviolet corona discharges on treetops during storms

#64

Post by colanderman »

addaon wrote: post #10
colanderman wrote: post #3

There is in fact no photograph of treetops glowing. There is a digital UV-wavelength video of the corona, and a visible-wavelength video of the trees. The paper [1] contains a sole picture with tiny circles indicating where the UV-video detected corona events, overlaid over a frame of the visible-wavelength video. The paper does also contain a video [2] which overlays a somewhat processed version of the UV video over…

Sorry, in what way is this not a photograph? Are you saying that a video is not a sequence of photographs, that UV photons captured by a sensor don’t count because human retina sensitivity is low in that range, or some hopefully-less-semantic argument?

Which photograph? The one in the article is not from the paper. The paper contains no photographs of corona.

Re: Ultraviolet corona discharges on treetops during storms

#65

Post by colanderman »

arrowleaf wrote: post #11
colanderman wrote: post #4

Earlier quoted context omitted.

[flagged]

Human eyes can be sensitive down to 380nm, the UV range goes up to 400nm. Birds and insects can see this. We can see this, using UV filters such as shown in the article. I get that it's fun to be a pedant sometimes, but come on.

I did not state that humans cannot see corona.

Nor is the paper is about humans seeing corona.

It is about detecting UV photons using specialized equipment.

Re: Ultraviolet corona discharges on treetops during storms

#66

Post by _Microft »

colanderman wrote: post #3

There is in fact no photograph of treetops glowing. There is a digital UV-wavelength video of the corona, and a visible-wavelength video of the trees. The paper [1] contains a sole picture with tiny circles indicating where the UV-video detected corona events, overlaid over a frame of the visible-wavelength video. The paper does also contain a video [2] which overlays a somewhat processed version of the UV video over…

Half of the comments are in this subthread which derailed the discussion on this submission before it even started. Here the damage is done but maybe, please, refrain from doing so elsewhere.

Re: Ultraviolet corona discharges on treetops during storms

#67

Post by steve1977 »

latexr wrote: post #28
raincole wrote: post #27

Earlier quoted context omitted.

That's some weird semantic nitpicking. Wikimedia has a category of "photographs of the Sun": https://commons.wikimedia.org/wiki/Category:Photographs_of_t... Do you think they are not photographs of the Sun because these are not what I see if I look at the sun with my eyes? (In which case I'll see pure white then perma black, I assume.)

> then perma black, I assume. Probably not. https://www.bbc.com/news/blogs-ouch-31487662

While reading I thought this is basically visual tinnitus and then the author used exactly that term. As someone with tinnitus, I can definitely understand the longing for "absolute darkness".

Re: Ultraviolet corona discharges on treetops during storms

#69

Post by Melatonic »

dlcarrier wrote: post #42

The lines about oxidizers cleaning the air reminds me of the aspects of late 1800's and early 1900's product marketing oversimplifying hygiene. Bleach everything, whether it needs it or not; anything that indiscriminately kills all bacteria can only make the world a better place!

To be fair with the lack of refrigeration and general spread of disease and vermin this could have been a great idea at the time
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