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In this video, around 2:24, one can see a flash of lightning that keeps the same form for a little time span. Does this mean that it takes a while before the discharge is complete (which I can't imagine) or that the electrons move to and fro between the Earth and cloud (or between the clouds themselves) before the discharge is complete? I can imagine that extra electrons move behind the discharge which on arrival on Earth flash back, taking extra electrons back, etc. But in this case, the flash should dim over time. So why the flash remains in a steady shape that long?

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Lightning is a rapid transition from a non-conducting to a conductive state.lightning creates an ionized, electrically conductive channel through air inside the cloud,between clouds or between cloud and earth.The high electric field accelerates the electrons between the channel.When they collide with air molecules, they create additional ions and newly freed electrons which are also accelerated.So it takes some time.Electrons will only flow against the electric field.they don't oscillate.

Once the gap breaks down, current flow is limited by the available charge (for an electrostatic discharge) or by the impedance of the external power supply. If the power supply continues to supply current, the spark will evolve into a continuous discharge called an electric arc

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    $\begingroup$ Re, "Electrons will only flow against the electric field.they don't oscillate." The clouds and the Earth and the air gap between them constitute a giant capacitor, and the plasma channel (like any conductive path) exhibits inductance. Put a capacitor and inductor in series with each other, and you have a resonator. The current in a typical cloud-to-ground lightning stroke can change direction thirty times or more before it dies out. $\endgroup$ – Solomon Slow Apr 9 at 12:55
  • $\begingroup$ @Solomon Slow I think you should expand that into a full answer. I don't have a good sense for the $L,R,C$ in this situation, so that should be very informative. $\endgroup$ – KF Gauss Apr 9 at 16:02
  • $\begingroup$ So when the path is created they only make room for more electrons to make the journey downwards instead of the electrons going all downwards in one short flash? I.e., they are getting down in almost invisible (you cán actually see the flash getting bright-less bright-bright-etc.) pulsed way? $\endgroup$ – descheleschilder Apr 9 at 18:21
  • $\begingroup$ Yes they collide with air molecule and make new ions thats why we can see lightning easily $\endgroup$ – user227513 Apr 9 at 19:44

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