Subject: During a lightning storm, why does the ground become positively charged?

We are studying lightning and electricity in science. Our book said, " Winds separate the charged particles, cousing the upperpart of the cloud to become positively charged. The bottom part, or base of the cloud becomes negatively charged.

The negative charge at the base of the cloud repels negative charges in the ground below the cloud. So, the surface of the ground beneath the cloud becomes positively charged."

We didn't understand how the ground could become positively charged when it was just negatively charged and repelling the negatively charged part of the cloud.

Re: During a lightning storm, why does the ground become positively charged?