Is lightning caused by the cloud acting as a capacitor?

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Discussion Overview

The discussion centers around the analogy of lightning and capacitance, exploring whether the behavior of thunderstorms can be understood through the concept of a cloud acting as a capacitor. Participants examine the mechanisms of charge separation in clouds and the conditions leading to lightning strikes, considering both theoretical and observational aspects.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant describes the process of charge separation in thunderstorms, likening it to the behavior of a capacitor.
  • Another participant agrees that the separation of charges with air acting as a poor conductor resembles a capacitor's function.
  • One participant suggests that lightning occurs when the capacitance of air is exceeded, allowing charge transfer from clouds to the ground.
  • A different viewpoint acknowledges the description of charge dynamics but notes that the current understanding does not fully explain all observations related to lightning.
  • Another participant argues that while capacitance is involved, the semantics of whether it "causes" lightning are debatable, suggesting that discharges would still occur in a different form without capacitance.
  • One participant introduces the concept of Transient Luminous Events (TLEs) as a related phenomenon, indicating additional complexity in the discussion.

Areas of Agreement / Disagreement

Participants express both agreement on the analogy between lightning and capacitance and disagreement regarding the implications of this analogy. There is no consensus on whether capacitance is a causal factor in lightning, and the discussion remains unresolved regarding the completeness of current explanations.

Contextual Notes

Some participants note that the current paradigm does not account for all observed phenomena related to lightning, indicating potential limitations in the existing models and assumptions about charge dynamics.

ChromeBit
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So I was looking up what causes thunderstorms online and found this:
"As hail moves within the cloud it picks up a negative charge by rubbing against smaller positively charged ice crystals. A negative charge forms at the base of the cloud where the hail collects, while the lighter ice crystals remain near the top of the cloud and create a positive charge.

The negative charge is attracted to the Earth's surface and other clouds and objects and when the attraction becomes too strong, the positive and negative charges come together, or discharge, to balance the difference in a flash of lightning (sometimes known as a lightning strike or lightning bolt). The rapid expansion and heating of air caused by lightning produces the accompanying loud clap of thunder."

The line that really interested me was this: "and when the attraction becomes too strong, the positive and negative charges come together". This sounds to me like a capacitor.

Am I correct in thinking this or am I mistaken?
 
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Well, you have separated charges with a bad conductor (air) in between, that is similar to a capacitor.
 
(i think) you have thought a correct analogy between lighting and capacitance . What i think is that when lighting strikes them the maximum capacitance of air is crossed and the charge is finally transferred from clouds to the land .
 
ChromeBit said:
Am I correct in thinking this or am I mistaken?
You have described the currently accepted paradigm correctly. Unfortunately it does not explain everything that is observed and so will be subject to revision at some time in the future.

When the potential difference between two parcels or pools of opposite charge exceeds the breakdown voltage of the air, an ionised path called lightning forms that discharges the local charge difference.

There is capacitance between the two parcels of air and there is a charge difference. The voltage is therefore V = Q / C, derived from the definition of capacitance C = Q / V.
 
To answer the question you posed in the title, whether capacitance "causes" lightning is a matter of semantics.
Without the capacitance, there would still be a discharge, but it would have to be a continuous current. It would not be lightning-like.
 
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