Where does lightening come from, clouds, ground or both?

Asked by: Jason

Answer

First of all, to be vague, it comes from both but starts in the cloud.

A combination of air currents and moving ice and water particles in the cloud causes positive and negative charges to separate. Put simply, the positive charges gather near the top of the cloud and the negative charges gather near the base.

Once an appreciable negative charge has built up on the bottom of the cloud, a 'shadow' is created on the ground below where a positive charge is induced. The conditions are now right for a lightning strike.

Once the charge on the cloud is big enough, a small path of negative charge makes its way towards the ground. Once it gets close, a path of positive charge leaves the ground and heads up to meet it.
Answered by: Corey Taylor, Undergrad, Florida Institute of Technology