# Is during lightning clouds losses some its mass?

1. Sep 4, 2011

### joyever

during lightning when two clouds attract each other on that time, they loss some of its mass??

2. Sep 4, 2011

### xts

They lose lots of their mass - lightnings usually occure during heavy rains - all that water/snow/hail falling on your head during thunderstorm is losed by cumulonimbus cloud.

3. Sep 4, 2011

### KingNothing

Are you asking if the electron flow from the lightning affects the mass? In that case, I guess it would very slightly. I'm not sure if the electrons flow into or out of a cloud.

4. Sep 4, 2011

### xts

There are both positive and negative lightnings, actually positive (cloud-positive, ground-negative) are more common.

But before you think about subtle effects like electrons flowing or relativistic mass loss due to emission of energy (light and sound): answer yourself, what do you mean by 'mass of the cloud'?

5. Sep 4, 2011

### klimatos

Clouds are phenomena consisting of many different kinds of ongoing actions. They are dynamic, not static. They have no fixed boundaries, no fixed mass, no fixed anything.

Intracloud lightning is far more common than intercloud lightning. There is no significant "attraction" between clouds during lightning events or at any other time.

6. Sep 5, 2011

### jewbinson

So clouds don't have electric charge? (stupid question but whatever)

7. Sep 5, 2011

### xts

They have.
So now a little excercise for you: google for data such as a voltage thunder clouds have, charge which is discharged during the lightning, typical sizes of cumulonimbus clouds.
Think how you may estimate (define) the 'mass of cloud'.
Then use a school physics of electrostatic force and Newtonian dynamics to compute what is the force between clouds, and what acceleration may such force impose to such mass.
Then go out during the thunderstorm to feel on your face what are wind conditions during the thunderstorm.
Then go back to school physics and estimate, what force such wind impose to a sphere of the size of the cloud.
Then compare the electrostatic force with wind force.

8. Sep 5, 2011

### klimatos

I don't consider it to be a stupid question. Curiosity should always be encouraged.

Yes, the individual droplets that make up a cloud may (or may not) have an electrostatic charge. These individual charges are quite weak and the distances between clouds so great in comparison that no significant attraction or repulsion forces can be measured with the instruments we have today.

I believe that the OP dealt with mass transfer during lightning events. Lightning involves the transfer of electrons and electrons have mass so mass transfer does take place. However, we have no evidence that would lead us to believe that clouds move closer to one another or farther away during such events.

Remember, scientific belief is based on evidence and evidence only.

9. Oct 2, 2011

### joyever

10. Oct 2, 2011

### xts

If you expect school answer: 'yes, the equation e=mcÂ˛, energy is released, so the mass is lost.
If you expect more physical answer: 'there is no definition of what the mass of cloud is precise enough to justify speaking about such effects'.
If you want yes/no physical answer: try to define what do you mean by 'mass of the cloud'. To make your task easier, here are several propositions not precise enough:
- sum of masses of all droplets;
- sum of mass of all matter in the volume delimited by some fixed shape;
- sum of mass of all matter in the volume defined as non-transparent (in contrast to surrounding transparent air).

11. Oct 2, 2011

### joyever

So if we consider it as total mass of droplets what would be the answer?

12. Oct 2, 2011

### joyever

So if we consider it as total mass of droplets what would be the answer?

13. Oct 2, 2011

### xts

The answer is: lots of droplets fall to ground and sink there. Some droplets grow bigger and heavier, as water vapour condense on them. Some other lose their mass due to vapourisation. Overall balance is: the cloud usually loses lots of its mass, dominantly due to raining. However, in an early stage of thunderstorm, it is still growing.
Relativistic effects are many orders of magnitude smaller than that so they pay no noticeable contribution.

14. Oct 4, 2011

### joyever

The question here is not about droplets. My question is would mass be lost during lightening as energy is released..

15. Oct 4, 2011

### xts

I see some inconsistency in your question.

Asking about very subtle effects (as I inderstand your doubts - it is about mass energy equivalence - this is extremely subtle effect) you must propose a method (even technically unable to realize) of experiment answering this question. Your proposition was: measure the mass of all droplets in the cloud, wait for the lightning, measure the mass again, compare masses. I predicted the result of your experiment, giving even some realistic explanation why the results would differ.

I doubt you may provide the definition of 'cloud mass', consistent with common meaning of what 'cloud' and 'mass' are, in which your relativistic effect could be seen.

The cloud is not an isolated system - it is a dynamic structure, all the time interacting and exchanging its matter and energy with surroundings.

16. Oct 4, 2011

### klimatos

If you mean is mass converted into electrical energy during a lightning strike, then the answer is no. A lightning strike is the transfer of electrons from place A to place B. The electrons are not destroyed in the transfer, and lose no mass.

Einstein's equation refers primarily to the conversion of matter into energy during nuclear fission and fusion. It does not refer to the release of energy by chemical means (the burning of fuels, for instance) or the release of energy by electromagnetic means (the heating of the filament in a light bulb, for instance).

The above paragraph has to be modified in advanced physical discussions, but serves well to answer your OP.

17. Oct 4, 2011

### joyever

thanks for solving my question