Cause of Lightning - Understand How It Happens

[AlchemistK]

Lightning is quite a common phenomena and yet i don't have a clear understanding of how it is caused.
Can someone tell me the real cause of lightning?

 

[S.Mukherjee]

Actually lightning is created due to huge potential difference created between cloud and earth.Clouds due to rubbing with each other create huge amount static charge which has very high potential with respect to earth.Now, the electric field thus created is very strong resulting in ionisation of air particles in between cloud and earth.These ionised air particles(also called plasma)acts as a conducting layer and transmits huge amount of current creating thermal radiations lying in visible region.

 

[AlchemistK]

But isn't static charge created by friction from clouds just one of the theories?
I have read others which include ice which causes forced separation of charges.