Hello. As far as I know, every circuit capable to flow current must be closed. In other word, open circuit can not flow the current, obviously. Right now, I would like to know this is also true for lighting in bad weather. When bottom of the dark and heavy cloud get more and more electron by convectional flow inside the cloud (positive charges are accumulated at the top of the cloud), air breakdown occurs once voltage between cloud and ground overruns breakdown voltage of the air. Then current flows from the cloud to ground. I believe majority carrier of this current is electrons from cloud. In circuit theory, this current must be within closed circuit. But I don't see what is closed loop in this case. It looks like current flow doesn't requires closed loop at first glancing. How can I overcome this apparent contradiction?