Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

My chemistry teacher/book states that lightning is just light, and therefore has no mass and takes up no space (we're not very far through the book yet, it's defining matter).

However, I take issue with this statement - it feels wrong. My reasoning is this: Lightning, as far as I know, is simply electrical energy. Also, I believe that electrical energy needs a medium to travel through, right?

If this is true, wouldn't the air the lightning travels through be the mass and space the lightning takes up?

share|cite|improve this question
up vote 11 down vote accepted

Lightning is not 'just light', it is according to this NOAA National Severe Storms Laboratory FAQ,

Lightning, as best we understand, is a channel of electrical charge, called a stepped leader that zigzags downward

So, technically speaking, the mass of a lightning bolt could be the sum of all the electrons and the plasma within the electrical charge channel. (thank you to tpg2114)

Each electron has a mass of about $9.11 × 10^{-31}$ kilograms, but it would not really be feasible to exactly count how many electrons there are in a single lightning bolt, hence, not feasible to get an exact mass.

share|cite|improve this answer
The light itself is caused by an electrical charge which creates a plasma in the air through which it travels. So I would say that if you wanted to "weigh" a lightning bolt, you would have to take the weight of the plasma, not just the electrons. – tpg2114 Sep 23 '13 at 14:57
@tpg2114 yes, that is why I said lightning is not just light (as the OP's teacher claims) – user29350 Sep 23 '13 at 14:59
Sure, but you claim So, technically speaking, the mass of a lightning bolt would be the sum of all the electrons within the electrical charge channel. which I disagree with. It should be the weight of the plasma, which is not just the electrons. – tpg2114 Sep 23 '13 at 15:01
Of course, if you don't agree with my disagreement, you can leave your answer as is and I can post my own when I get some time :) – tpg2114 Sep 23 '13 at 15:01
@tpg2114 I agree with you, just had not had the chance to edit until now...thank you for the additional insight. – user29350 Sep 23 '13 at 15:04

It depends on how you define "lightning". When electrons flow from clouds to the earth, ionizing the air and producing light, does your definition include the electrons, the air, the plasma, the light, or a subset?

Pedantically speaking, I would say that lightning is the flow of electrons, and to me a flow is an abstract idea (the action of moving in a steady, continuous stream) instead of a concrete object with a mass.

share|cite|improve this answer

Lightning must have some mass, how else is thunder created. If thunder is the sonic boom created by lightning moving faster than the speed of sound, then lightning must have mass. I don't hear thunder every time I turn a flashlight on.

share|cite|improve this answer
uhhhh... sorry but this post is so wrong, i am going to need a moment... i don't know who told you that thunder is the sonic boom created by lightning moving faster than the speed of sound, but you should inform them they need to go back to gradeschool. After lightning strikes it heats up the air along its patch for a fraction of a second to a really high temperature, the rapid expansion of this air is what causes the thunder. And just FYI - lightning and flashlights have very little in common. :) – mathgenius May 4 '15 at 14:10

protected by ACuriousMind Aug 20 '15 at 2:15

Thank you for your interest in this question. Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).

Would you like to answer one of these unanswered questions instead?

Not the answer you're looking for? Browse other questions tagged or ask your own question.