Incredible pic of Red Sprite Lightning

DaveC426913 said:
This is a relatively newly discovered phenomenon, reported by eyewitnesses for a century but only
first photographed (accidentally) in 1989.

And this is just a low-rez sample ...
View attachment 5653

Click through! Click through!
https://apod.nasa.gov/apod/ap231002.html
Then click on the page image - once to open the image in the window, then again to see it full size.
Click to expand...
Beautiful picture. There seem to be several atmospheric electrical phenomena that remain to be explained satisfactorily. Ball lightning is another.
 
exchemist said:
Beautiful picture. There seem to be several atmospheric electrical phenomena that remain to be explained satisfactorily. Ball lightning is another.
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Ok this is from the History Channel so although not foolproof it has some legs. I have no idea on the physics of these things.

 
Pinball1970 said:
This is a personal channel so not as robust as a news Channel or History Channel.

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Hmm, as a rule I don't watch YouTube videos and there's something fishy about the picture. Red sprites are a very high altitude phenomenon (ionosphere?) and extremely transient.
 
exchemist said:
Hmm, as a rule I don't watch YouTube videos and there's something fishy about the picture. Red sprites are a very high altitude phenomenon (ionosphere?) and extremely transient.
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All the videos are sped up too. I'll see if I can find something on National Geographic or News channel.
 
The ball lightning. Post #4.
The first video showing the rail tracks ball lightning, at time mark 3:35 it was admitted the effects were CGI. I’m left wondering whether they meant the ball itself was CGI or was the 'sparking out' the CGI?
 
exchemist said:
A document, rather than a video, would be nice:smile:.
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Lighting striking the ground and heating chemicals in the soil…
There’s a good comic-picture depiction of the process of this idea on the linked page.
It only theory still, but this is rather good.
https://www.dos4ever.com/bolbliksem/bolbliksem.html
For a science fair, Martijn created some cartoons that illustrate the theory from Abrahanson and Dinniss (Fig. 1). At the high temperatures created by the lightning strike, the carbon in the soil chemically reduces the silicon-dioxide to the vaporized, metallic form of silicon. The fast-cooling of the hot vapour condenses the silicon into an aerosol of nanometre sized filaments. Electrical charges created in the heat gather around the surface of the aerosol, binding it together and the resulting ball starts to glow since the silicon starts to oxidize with the oxygen from the air. The oxidation rate however, is limited by the need of the oxygen to diffuse through the developing silicon-oxide layer at the surface of the ball [1].
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Ps. The link courtesy of Mick West site.
 
foghorn said:
Lighting striking the ground and heating chemicals in the soil…
There’s a good comic-picture depiction of the process of this idea on the linked page.
It only theory still, but this is rather good.
https://www.dos4ever.com/bolbliksem/bolbliksem.html

Ps. The link courtesy of Mick West site.
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Interesting and they may be onto something regarding mechanisms for ball lightning, but as it stands I have problems with it. There are cases of ball lightning at sea and even on aircraft. And I myself have observed it in the tank farm of an oil plant, where the ground was concrete, not soil. Though there was a bit of oil around.
 
Pinball1970 said:
It is not quite a paper but National geographic article has some nice images

https://www.nationalgeographic.com/...onal-space-station-nasa-science-red-lightning

https://www.nationalgeographic.com/science/article/lightning-sprites-form-over-hurricane-matthew
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Nice pictures, though not a lot by way of information. I see that, contrary to what I had thought, it can be possible to see them from the ground if one is sufficiently far away from the thunderstorm responsible. They seem to occur in the mesosphere, 30-50 miles up. From what I have read so far they are not "sparks", as the person quoted in one article says, but discharges more akin to those in a fluorescent tube. That's what you would expect, I think, since the ionosphere contains a lot of ionised air molecules. I notice they say the red colour comes from excited states of nitrogen. However when you look up aurora borealis, you don't find red due to nitrogen. I'll have to look into that some more.
 
Pinball1970 said:
It is not quite a paper but National geographic article has some nice images

https://www.nationalgeographic.com/...onal-space-station-nasa-science-red-lightning

https://www.nationalgeographic.com/science/article/lightning-sprites-form-over-hurricane-matthew
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I have found a quite detailed paper investigating sprites here: https://digital.csic.es/bitstream/10261/222445/1/IAA_2020JGRD..12533170S.pdf

Evidently the red colour is due to various emissions bands of the N2 molecule, which they describe with historical terminology from classical lab experiments with discharge tubes. Hence for instance they talk of the "first positive band" or the "second negative band" etc, these being references to whether the glow would be seen towards the anode or the cathode of a gas tube. (I had to spend a bit of time to research and understand this, as it was terminology unfamiliar to me from chemistry. Here's a link to how discharges in tubes are characterised:https://www.g3ynh.info/disch_tube/intro.html ) .

What's clear is that these sprites are a glowing discharge of the type seen in "neon" tubes, rather than the explosive arc seen (and heard) at ground level in a lightning bolt. This makes sense when one appreciates how thin the air is at the altitudes where they occur.

It seems the mechanism is as in a discharge tube: an electric field causes electrons and ions to be accelerated to velocities at which, when they collide with molecules of nitrogen, they are able to kick them into certain electronically excited states. These radiate when they return to the ground state, each emission band being due to a particular excited state, which can be identified from the wavelength range of the emission, using a spectrometer.

Apparently too the electric field and/or the stream of electrons that initiates the sprite are triggered by a lightning discharge, the glow appearing a few milliseconds after the lightning flash.

This is all rather fascinating, I must say. The mechanism of charge separation in thunderstorms is still poorly understood and this activity far above the cloud tops adds a further area of study.
 
Last edited:
DaveC426913 said:
This is a relatively newly discovered phenomenon, reported by eyewitnesses for a century but only
first photographed (accidentally) in 1989.

And this is just a low-rez sample ...
View attachment 5653

Click through! Click through!
https://apod.nasa.gov/apod/ap231002.html
Then click on the page image - once to open the image in the window, then again to see it full size.
Click to expand...
Thanks for this thread, Dave. It has made me do some reading on the subject. Good science!
 
DaveC426913 said:
I would be very interested in hearing your account of the incident.
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This was a long time ago, 1982 or so, so my memory isn't very exact. I was in my office in the admin block of the oil plant when there was a thunderstorm. At one point there was a loud bang - evidently lightning had struck some piece of the tank farm across the yard. Anyway I looked out of the window, to make sure that was all it was. I then saw a globe, about a couple of feet across, not specially bright but glowing gently, moving slowly and silently along, just above the ground. I can't be sure whether it was touching either the ground, or a pipetrack or the brick wall of the bund, or else floating in the air above. The ground was concrete and wet obviously. There was also a bit of oil around (this was a lubricants plant and if one spilt a bit it was hard to get it all cleaned up), so maybe that could have contributed to some species that could be volatilised by lightning. The ball moved slowly for a few yards and then silently vanished. I'd been rather doubtful that ball lightning was real up to that point. Looking now at other people's reports of it, it seems my experience fits with that of others.
 
I spotted this on another site https://apod.nasa.gov/apod/ap230918.html

SpriteTree_Villaeys_1333.jpg
 
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