The Physics of Lightning

[Cloggy Mike]

I have some questions regarding lightning:

1. In collisions of ice particles electrons are said to move towards larger ice particles. Why would electrons have a preference for larger ice particles and what is the physical mechanism that promotes the transfer of electrons during collisions of ice particles?
2. During lightning electrons flow from the air to the earth. How does the air get replenished with electrons?

Many thanks in advance for your responses.

[Methuselah]

9 minutes ago, Cloggy Mike said:

I have some questions regarding lightning:

1. In collisions of ice particles electrons are said to move towards larger ice particles. Why would electrons have a preference for larger ice particles and what is the physical mechanism that promotes the transfer of electrons during collisions of ice particles?
2. During lightning electrons flow from the air to the earth. How does the air get replenished with electrons?

Many thanks in advance for your responses.

Welcome to NW, Cloggy Mike.

As far as Q1 is concerned, I have not the foggiest. Q2 though might just be different? Excess electrons from the ground move (invisibly) upwards in their effort to reach the protons that (usually) hang around somewhere near the cloud-base...Once the two connect, the potential (difference in voltage?) then zaps toward the ground producing the lightning that we can see? That, I believe is a 'negative' stroke (as the leader, electrons?) provide the upward 'leader'? 

That might be all a load of codswallop? But, if it isn't, you'll need 'A. N. Other' to explain a positive stroke...I know nothing, I'm from Barcelona!

[Jo Farrow]

Hi Cloggy Mike, is the ice particle question to do with lightning

Do you mean like in Aggregation growth when ice particles grow by colliding and adding to other ice particles?

[Cloggy Mike]

1 minute ago, Jo Farrow said:

Hi Cloggy Mike, is the ice particle question to do with lightning

Do you mean like in Aggregation growth when ice particles grow by colliding and adding to other ice particles?

Yes. The source of the electric charge of lightning is said to be that the heavier negatively charged ice particles accumulate in the bottom of the cloud and that the lighter positive ones accumulate at the top. I am wondering why the bigger ice particles become negative.

[Relativistic]

On 05/09/2016 at 16:53, Ed Stone said:

As far as Q1 is concerned, I have not the foggiest.

 

On 05/09/2016 at 17:07, Cloggy Mike said:

Yes. The source of the electric charge of lightning is said to be that the heavier negatively charged ice particles accumulate in the bottom of the cloud and that the lighter positive ones accumulate at the top. I am wondering why the bigger ice particles become negative.

I did construct an argument but did some calculations and realised that it was totally flawed!

I have found this link though, which says the following:
"For reasons not yet fully understood by scientists, it is thought that smaller particles (less than 100 micrometers) acquire a positive charge, while larger particles gain a negative charge."

http://www.aharfield.co.uk/lightning-protection-services/how-lightning-is-formed

So it looks as if it is still a mystery waiting to be solved.

Edited September 12, 2016 by Relativistic

[Cloggy Mike]

Relativistic, thanks for your reply. Your constructed answer sounded plausible for the initial charge, but I was wondering if this would be enough to generate the energy required for lightning. I am not sure what the particle density is, but remember reading that some recent doppler interpretation work was looking at droplet / particle size distribution in clouds. Quite surprising that such fundamental questions don't have readily available explanations. Maybe a nice subject for a phd research project.