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Does lightening cause a form of cavitation?

  1. Jun 7, 2012 #1
    Does lightening cause cavitation of air much like in a normal fluid?

    It moves through the air so fast it has the same effect and then we hear thunder as a result?
     
  2. jcsd
  3. Jun 7, 2012 #2
    Cavitation is the creation of bubbles that release energy when they pop. I don't think just air can form bubbles by itself, it would need a liquid to contain it. The lightening is ionizing the air and heating it to a plasma. I don't know if there are such thing as plasma bubbles and so I don't know the answer to your question.
     
    Last edited: Jun 7, 2012
  4. Jun 7, 2012 #3
    Dragon is correct, that this cannot be cavitation the way we normally understand the term. But it is something similar. With such rapid heating of the air, you have very rapid expansion. That is followed by very rapid cooling and a collapse of the air back to something close to its original volume. This is what makes the noise.

    In cavitation, you have a rapid expansion of a gas bubble, followed very quickly by its collapse. Similar, but different.
     
  5. Jun 8, 2012 #4

    Bobbywhy

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    Gold Member

    From Wikipedia:
    "Because the electrostatic discharge of terrestrial lightning superheats the air to plasma temperatures along the length of the discharge channel in a short duration, kinetic theory dictates gaseous molecules undergo a rapid increase in pressure and thus expand outward from the lightning creating a shock wave audible as thunder. Since the sound waves propagate, not from a single point source, but along the length of the lightning's path, the sound origin's varying distances from the observer can generate a rolling or rumbling effect."
    http://en.wikipedia.org/wiki/Lightning

    Cavitation in fluids is quite different from lightning. You may Google it to learn more.
     
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