What Determines the Zig Zag Pattern of Lightning?

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Discussion Overview

The discussion revolves around the factors influencing the zigzag pattern of lightning, exploring its predictability, the behavior of charge carriers, and the underlying physics of lightning strikes. Participants examine various theories and models related to lightning's path, including ionization, the role of electric fields, and the effects of environmental conditions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants propose that lightning is predictable, while others argue it exhibits randomness, suggesting a complex interplay of linear and non-linear dynamics.
  • There is a discussion about whether lightning charge carriers gain enough momentum to overcome forces acting on them, with some suggesting relativistic speeds in air but not in conductors like copper.
  • Participants mention the importance of the ionization path, or leader, in determining lightning's trajectory, with various hypotheses about its formation including cosmic rays and variations in air composition.
  • One participant highlights that the electric and magnetic fields associated with lightning are often modeled as straight channels, which may not accurately reflect the tortuous and branching nature of real lightning paths.
  • Questions arise about whether the fractal nature of lightning paths influences the electromagnetic fields produced or vice versa.
  • Some participants note that the path of lightning can change during the discharge process, complicating predictions about its shape.
  • There are observations regarding the behavior of lightning as it leaves conductors, with discussions on whether it completely exits or finds parallel routes, particularly in the context of fiberglass hulls on boats.
  • Experiences from the telecommunications industry are shared, emphasizing the importance of avoiding sharp bends in conductors to prevent lightning from jumping to unintended paths.

Areas of Agreement / Disagreement

Participants express multiple competing views on the predictability of lightning and the factors influencing its path. The discussion remains unresolved, with no consensus on the primary determinants of lightning's zigzag pattern.

Contextual Notes

Limitations include the dependence on various assumptions about the behavior of charge carriers, the complexity of environmental factors, and the unresolved nature of the mathematical models used to describe lightning.

  • #31
jerromyjon said:
The impedance simplifies to resistance in direct current, from what I've read. I'm still trying to fit the whole puzzle together.

I think the pinch you were referring to is caused by the current organising so that the magnetic field helps to condense the stream, meaning the current precedes the pinch not the pinch precedes the current.

It is obviously a complicated phenomenon but I'm determined to figure it out!
Current can (temporarily at least) travel through a capacitor. Then, at least theoretically, the current could form a magnetic field which forced the current to continue after the capacitor filled. Think of it as a small inductor in series with a low voltage capacitor. The inductor could easily break down the capacitor with careless design.

Of course that assumes the hull acts as a high value capacitor, which it doesn't under normal conditions. It's an unlikely explanation; probably more BFM.
 
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  • #32
I really think I'm missing something right in front of my face, but I can't see it. I keep looking at the leaders coming out of the ground, wondering why current would be going the wrong way. I wonder if that could be + ions being drawn towards the - charged cloud?
 
  • #33
jerromyjon said:
wondering why current would be going the wrong way.

what do you mean by that ?

jerromyjon said:
I wonder if that could be + ions being drawn towards the - charged cloud?

a good probability

and don't forget that the charge polarities can also be the other way around

Dave
 
  • #34
davenn said:
what do you mean by that ?
I meant I was stuck in a rut only considering the electrons and not the ions. Electrons wouldn't be coming out of the ground going towards the cloud while the electrons in the cloud are going towards the ground, that wouldn't make sense.
davenn said:
and don't forget that the charge polarities can also be the other way around
That was when it dawned on me, it goes either way for either polarity. It does make much more sense now. The leaders from the ions would be less "mobile" than the electrons, wouldn't they? That would explain why the branches are much more prominent on the electron side. Now I'm curious if I can find slo-mo of lightning going from ground to cloud... I think it would look different if charges were reversed.

It appears I am correct.:wink: Now I just have to figure out how the connection is formed to start the "seek and destroy" (discharge)
 
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  • #35
jerromyjon said:
I meant I was stuck in a rut only considering the electrons and not the ions. Electrons wouldn't be coming out of the ground going towards the cloud while the electrons in the cloud are going towards the ground, that wouldn't make sense.

That was when it dawned on me, it goes either way for either polarity. It does make much more sense now. The leaders from the ions would be less "mobile" than the electrons, wouldn't they? That would explain why the branches are much more prominent on the electron side. Now I'm curious if I can find slo-mo of lightning going from ground to cloud... I think it would look different if charges were reversed.

It appears I am correct.:wink: Now I just have to figure out how the connection is formed to start the "seek and destroy" (discharge)

Charge mobility is different for different charges. The most mobile seem to be electrons. The next most mobile are holes I think with about ⅓ the electron's mobility. Holes exist in semiconductor material in what I assume is a quantum effect. They are unfilled electron shells which act as positive charge carriers even though the constituent atoms are locked in a matrix. I mention them to show there are other possible charge carriers than electrons or ions. (I don't know which work in plasma though.)

Ions are several thousand times more massive than electrons and should be much slower for that reason. But I suspect Anorlunda's :nb) Quantum Electrodynamics would be needed to figure out which charges are moving where.

Also, cloud charges are sometimes reversed. I seem to recall reading this is common in monsoon storms for some reason. It is infrequent (I've read 10%) in temperate storms. Anyway, I tend to discount which charge is which for this reason, though perhaps that's a mistake.
 
  • #36
In the ground. The melted sand. Fulgurites also exhibit jaggedy branchings. different looking but oddly frozen in motion. maybe measurable consistencies in the distribution of branch endings. Any body know where this potential study is?
 
  • #37
Hi and welcome to PF! Thanks for joining the discussion.
EE Comp said:
The melted sand. Fulgurites
I am sure I've seen these at some point, but never remembered until you mentioned them, very much appreciated!

I'm definite I have the system down in my mind but I don't know how to relate all the variables just perfectly. It has quantum roots so prediction is probable but certainly not classic.
 
  • #38
  • #39
jerromyjon said:
http://www-solar.mcs.st-andrews.ac.uk/~alan/sun_course/Chapter2/node11.html
The "frozen-in" theorem, is just saying the magnetic field stays fixed to the plasma pinch, correct? So as the "electron gas" as if it were a Bernoulli relation drags the field with it across the counteracting ions... you get the "z" pinch?

I looked at the link you provided, and I also read about Alfvén's frozen in theorem on Wikipedia. Sorry, but I don't understand what they are saying, or how those relate to the question in this thread. Can you elaborate please?
 
  • #40
jerromyjon said:
http://www-solar.mcs.st-andrews.ac.uk/~alan/sun_course/Chapter2/node11.html
The "frozen-in" theorem, is just saying the magnetic field stays fixed to the plasma pinch, correct? So as the "electron gas" as if it were a Bernoulli relation drags the field with it across the counteracting ions... you get the "z" pinch?
I'm a bit confused.

The frozen in theorem seems to apply in a PEC fluid. But it's not clear to me that it applies in an intense electric field (which is sort of the opposite of a PEC).

I can understand how a moving stream of charge carriers (perhaps an electron gas) could be modeled as having a fixed magnetic field around it (with the field moving at the same speed as the gas). But I am missing the insight this view brings.

The frozen in theorem seems to allow charges to move only along field lines. The field lines are circular around the current path. Are you claiming the charge carriers will spiral along the current path? If so, how is this relevant? Or are saying this is the mechanism that keeps the current in a single(ish) stream?
 
  • #41
Jeff Rosenbury said:
Or are saying this is the mechanism that keeps the current in a single(ish) stream?
Yeah pretty much what I'm getting at. The plasma pinch goes up into the cloud normally. That's the + ions. The branching down from the clouds is the + ions going up.
 
  • #42
Jeff Rosenbury said:
I've been taught that lightning is somewhat random.
Do lightning charge carriers gain enough momentum to keep going despite the fairly strong forces bending them? In air, it would seem they might gain relativistic speeds (with millions of volts potential), but in copper? It doesn't seem likely. And if lightning wants to go straight so badly, why does it zig zag across the sky?
The lightning spreads (branches) in ways, that have the least resistance, that is the most conductive paths. These ionized and short-lived paths, ion channels (anions and cations) are formed already during the initialization phase of the lightning.
 
  • #44
Jeff Rosenbury said:
And if lightning wants to go straight so badly, why does it zig zag across the sky?

I don't really think the hilited bit is a valid assumption, considering all lightning discharges I have ever seen invalidate that statement