APOD: Gigantic Jet Lightning over China (2016 Aug 23)

[Guest]

The correct term for this phenomena is a "Sprite" (or "Lightning Sprites").

Will APOD correct all references to Lighting Jets?

This is not a sprite. It is some kind of jet. "Lightning" might reasonably be replaced with "TLE", but "sprite" would be wrong.

Whatever it is called, what kind of altitude are we looking at here for the red area above, the lightning middle part and the cloud top?

[Spif the Spaceman]

I wonder if cosmic rays could be a trigger for these discharges?

[kayakbob223]

Is the dotted streak (bottom left by the cloud top) a satellite or a spinning perseid?

Just an airplane.

Hum, if that is an airplane then how fast do you think it must be going, considering this is a single frame.

We are talking the streak just above the camera on the left side of the frame.

If you expand the picture to maximum size, the plane's red (port) light just becomes visible. There are about 9 stacked images of at least 2 second exposure each. Note the double strobe light for each exposure. the plane is moving right to left away from the camera. Note the ghost like images of the people as they move around.
Bob

[Ann]

I'd love to know what causes the colors.

This jet lightning is purple to violet near bottom and red at top. Could this be related to blue jets and red sprites, in that the blue jets are lower than the red sprites? Could both these phenomena (or related ones) be seen at different levels of one huge jet?

I'm guessing that:

• blue jets are from ionized nitrogen atoms that regain an electron after being ionized;
  
  while red sprites are from ionized nitrogen atoms that return to their ground state.
  
  Purple to violet gigantic jets are a combination (and/or) ARGON.

<<Auroras result from emissions of photons in the Earth's upper atmosphere, above 80 km, from ionized nitrogen atoms regaining an electron, and oxygen atoms and nitrogen based molecules returning from an excited state to ground state. They are ionized or excited by the collision of particles precipitated into the atmosphere. Both incoming electrons and protons may be involved. Excitation energy is lost within the atmosphere by the emission of a photon, or by collision with another atom or molecule:

oxygen emissions

• green or orange-red (630.0 nm), depending on the amount of energy absorbed.

nitrogen emissions

• blue: if the atom regains an electron after it has been ionized,
  red: if returning to ground state from an excited state.

Oxygen is unusual in terms of its return to ground state: it can take three quarters of a second to emit green light and up to two minutes to emit red. Collisions with other atoms or molecules absorb the excitation energy and prevent emission. Because the highest atmosphere has a higher percentage of oxygen and is sparsely distributed such collisions are rare enough to allow time for oxygen to emit red. Collisions become more frequent progressing down into the atmosphere, so that red emissions do not have time to happen, and eventually even green light emissions are prevented. This is why there is a color differential with altitude; at high altitudes oxygen red dominates, then oxygen green and nitrogen blue/red, then finally nitrogen blue/red when collisions prevent oxygen from emitting anything.>>

Click to view full size image

Figure 2: The schematic spectrum of a typical HII region, showing emission lines.
HII denotes a singly ionized hydrogen atom, NII represents a singly ionized
nitrogen atom, and OII and OIII denote singly and doubly ionized oxygen atoms.
Source: http://www.open.edu/openlearn/ocw/mod/o ... =1&id=2462

Thanks, Art, but I'm still confused.

According to the graph and the caption at left, singly ionized nitrogen emits red light on recombination, and this red color is just a little redwards of Hα. What sort of nitrogen emits blue light? I would expect blue light to represent a higher state of excitation than red light. Think of the Balmer series. Ever higher levels of excitation of the hydrogen atom leads to the emission of ever more shortwave and high-energy photons.

Ann

[neufer]

I'd love to know what causes the colors.

This jet lightning is purple to violet near bottom and red at top. Could this be related to blue jets and red sprites, in that the blue jets are lower than the red sprites? Could both these phenomena (or related ones) be seen at different levels of one huge jet?

I'm guessing that:

• blue jets are from ionized nitrogen atoms that regain an electron after being ionized;
  
  while red sprites are from ionized nitrogen atoms that return to their ground state.
  
  Purple to violet gigantic jets are a combination (and/or) ARGON.

<<Auroras result from emissions of photons in the Earth's upper atmosphere, above 80 km, from ionized nitrogen atoms regaining an electron, and oxygen atoms and nitrogen based molecules returning from an excited state to ground state. They are ionized or excited by the collision of particles precipitated into the atmosphere. Both incoming electrons and protons may be involved. Excitation energy is lost within the atmosphere by the emission of a photon, or by collision with another atom or molecule:

oxygen emissions

• green or orange-red (630.0 nm), depending on the amount of energy absorbed.

nitrogen emissions

• blue: if the atom regains an electron after it has been ionized,
  red: if returning to ground state from an excited state.

Oxygen is unusual in terms of its return to ground state: it can take three quarters of a second to emit green light and up to two minutes to emit red. Collisions with other atoms or molecules absorb the excitation energy and prevent emission. Because the highest atmosphere has a higher percentage of oxygen and is sparsely distributed such collisions are rare enough to allow time for oxygen to emit red. Collisions become more frequent progressing down into the atmosphere, so that red emissions do not have time to happen, and eventually even green light emissions are prevented. This is why there is a color differential with altitude; at high altitudes oxygen red dominates, then oxygen green and nitrogen blue/red, then finally nitrogen blue/red when collisions prevent oxygen from emitting anything.>>

Thanks, Art, but I'm still confused. What sort of nitrogen emits blue light?

According to https://en.wikipedia.org/wiki/Aurora "a nitrogen atom that regains an electron after it has been ionized"...whatever that means.

TLE jets might not be related to blue aurora at all(; after all, argon makes up ~1% of the atmosphere).

Why don't you do some investigating of the source of Transient Luminous Event colors? I, personally, am more interested in the fact that the two Chinese observations of gigantic jets took place during Perseid meteor shower periods. Is this just observational bias or are meteor showers actually seeding this phenomenon?

[Ann]

Interesting, Art. Indeed, that would be worth exploring. (Not that I would know how to do that.)

But like you said, does the onslaught of meteorites on the atmosphere cause (or aid) the appearance of TLE jets?

Or do people simply notice and photograph the TLE jets during the Perseid showers, because so many people are watching, photographing and filming the night sky during that time?

(But aren't TLE jets seen during other meteor storms? If so, why not?)

Ann

[geosource]

nice job with regards to finding andromeda Joe! i'm pretty good with that task and i missed it until receiving your tip.

[neufer]

Interesting, Art....But like you said, does the onslaught of meteorites on the atmosphere cause (or aid) the appearance of TLE jets? Or do people simply notice and photograph the TLE jets during the Perseid showers, because so many people are watching, photographing and filming the night sky during that time?

(But aren't TLE jets seen during other meteor storms? If so, why not?)

The Perseids "are a prolific meteor shower"
that occurs during the summer thunderstorm period in the Northern Hemisphere.

[BMAONE23]

In other words..
Correlation but not causation?

[Chris Peterson]

In other words..
Correlation but not causation?

Not even that given how easily this could just be observational bias. That is, the correlation may be purely observational and not actual.

It seems unlikely that meteors could be a factor, given that they burn up much higher than the cloud tops where jets appear to originate.

[neufer]

In other words..
Correlation but not causation?

Not even that given how easily this could just be observational bias. That is, the correlation may be purely observational and not actual.

It seems unlikely that meteors could be a factor, given that they burn up much higher than the cloud tops where jets appear to originate.

They could provide a conducting layer at the level where jets appear to end.

[Chris Peterson]

In other words..
Correlation but not causation?

Not even that given how easily this could just be observational bias. That is, the correlation may be purely observational and not actual.

It seems unlikely that meteors could be a factor, given that they burn up much higher than the cloud tops where jets appear to originate.

They could provide a conducting layer at the level where jets appear to end.

I don't think there's any evidence that meteors produce conducting layers. Their own path is briefly ionized, but we don't see things like differences in radio propagation during meteor showers (except for brief reflections off those ionized trails).

[neufer]

It seems unlikely that meteors could be a factor, given that they burn up much higher than the cloud tops where jets appear to originate.

They could provide a conducting layer at the level where jets appear to end.

I don't think there's any evidence that meteors produce conducting layers. Their own path is briefly ionized, but we don't see things like differences in radio propagation during meteor showers (except for brief reflections off those ionized trails).

Temporary ionized tendrils leading up to the ionosphere

P.S., I think that it is all observational bias too but it is fun to speculate.

[Chris Peterson]

They could provide a conducting layer at the level where jets appear to end.

I don't think there's any evidence that meteors produce conducting layers. Their own path is briefly ionized, but we don't see things like differences in radio propagation during meteor showers (except for brief reflections off those ionized trails).

Temporary ionized tendrils leading up to the ionosphere :?:

Well, Perseids actually burn up while still in the ionosphere. There aren't going to be many that extend below that, and none which will come close to the tops of thunderheads.

P.S., I think that it is all observational bias too but it is fun to speculate.

Certainly. This sort of brainstorming can lead to new ideas. Nothing wrong with it as long as we recognize it for what it is (and I don't doubt that you do... but we know of some that show up occasionally who place equal weight on speculation and solid scientific ideas).

[Astronymus]

Amazing image, amazing detail.

[Fred the Cat]

All sorts of astronomy news going on currently. Matthew is stirring up things in the Caribbean and Sol above it all.