Re: How does positive stroke lightning work?

Here are two websites that will (I hope) answer your question. Just one 
point of clarification: no mass is transferred in a lightning stroke. First, 
protons have no involvement in lightning - we are dealing entirely with 
ionized atoms (those which have lost electrons and hence are positively 
charged), and free electrons. The electrons themselves travel from atom to 
atom as the lightning stroke takes place, exactly as they would in an 
electrical cord. 
 http://www.lightningrod.com/manual5_how.html
 http://www.lightningstorm.com/lightningstorm/learning/index.jsp