Live data from Hacker News

Ultraviolet corona discharges on treetops during storms

psu.edu

41–50 of 69 posts

Re: Ultraviolet corona discharges on treetops during storms

#41
post #28

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

This was a very depressing read.

Re: Ultraviolet corona discharges on treetops during storms

#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!

Re: Ultraviolet corona discharges on treetops during storms

#43
post #19

Will head hair on humans do this too?

It's not very conductive, so it won't have any appreciable discharge, but the hairs will repel each other, which is easy to see. Search for "Van de Graaff generator" and "hair", to see lots of pictures.

Re: Ultraviolet corona discharges on treetops during storms

#44
post #28

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

What he explains sounds exactly like what you (or at least I) see when you close your eyes and then put pressure on them.

Re: Ultraviolet corona discharges on treetops during storms

#45

I once was about 30-50ft from where lightning struck, standing on my porch looking towards my neighbors' house. I didn't see the actual strike happen but I did feel my hair stand on end and then see basically this coming off of the leaves reaching up towards the sky. Little purple tentacles all reaching upwards. But then I got to the point in the article where they seemed to explain this wasn't visible to the naked e…

> I did feel my hair stand on end I've experienced this when a strike hit power lines above my head. I didn't see the actual strike either - my friend a the other end of the driveway said it was right above me, but that sounds a little hyperbolic to me despite the ringing in my ears. I think we'd both be dead if it were that close. Either way, it gave me a lifelong respect for lightning.

I've been indirectly hit by lightning, it struck my mom's house while I was running inside from the rain and at least part of it went through the wet iron handrail I was holding and hit me too.

I was super lucky as so much of it had bled off that it felt more like a slap that left me all tingly for hours.

Re: Ultraviolet corona discharges on treetops during storms

#46

I once was about 30-50ft from where lightning struck, standing on my porch looking towards my neighbors' house. I didn't see the actual strike happen but I did feel my hair stand on end and then see basically this coming off of the leaves reaching up towards the sky. Little purple tentacles all reaching upwards. But then I got to the point in the article where they seemed to explain this wasn't visible to the naked e…

The article said "nearly invisible to the naked eye" (emphasis mine). Between that and the fact the researchers weren't that close to an actual lightning strike (meaning you presumably would have seen a stronger effect), I would believe you saw something.

Re: Ultraviolet corona discharges on treetops during storms

#47

Earlier quoted context omitted.

Maybe they take issue with the word "glowing", which doesn't usually refer to invisible electromagnetic radiation

I was going to say the same. It's true that the image isn't fiction or a purely fabricated "artists rendering" from data. But it's also true that "filmed" and "glowing" are unusual ways to refer to what happened. You don't usually say filmed when talking about recording uv or microwaves etc. You technically could, and probably back when film was actually how uv was recorded a few people working in the field probably…

When I worked in a lab that took videos with a UV camera, I still called them videos, and I would absolutely have said that I took a video of the subject (a methanol flame in this case).

Essentially every color photograph you have ever seen is a composite of a red photographic, a green photograph, and a blue photograph.

Re: Ultraviolet corona discharges on treetops during storms

#48

I once was about 30-50ft from where lightning struck, standing on my porch looking towards my neighbors' house. I didn't see the actual strike happen but I did feel my hair stand on end and then see basically this coming off of the leaves reaching up towards the sky. Little purple tentacles all reaching upwards. But then I got to the point in the article where they seemed to explain this wasn't visible to the naked e…

You saw it, the human visual response curve is horribly uneven between individuals. Some can see fairly good into the UV range (especially those who have had cataract surgery,) while some can't even see 415nm violet but can see blue and red-mixed purple all day.

Re: Ultraviolet corona discharges on treetops during storms

#49
post #28

Earlier quoted context omitted.

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

What he explains sounds exactly like what you (or at least I) see when you close your eyes and then put pressure on them.

The way I had it explained was trying to look out one eye while the other’s closed

Re: Ultraviolet corona discharges on treetops during storms

#50
post #32

Earlier quoted context omitted.

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.

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…

I suppose this also depends on the types of remote controls? There are some where I can see red and some where I cannot.
Post reply on HN