During a thunderstorm, negative charges of electrical energy build up in the lower parts of clouds hovering close to earth. Conversely, positive charges develop in the ground, directly underneath the cloud. Lightning occurs when the dry air between the cloud and the ground is moistened by rain or high humidity. Lightning strikes start downward in 150-foot intervals.
In a lightning protection system, the positive ground charge is attracted upward through the conducting cables attached to the tree. When the negative downward stroke from the cloud is about 150 feet above the top of the protected tree, the positive ground charge leaps upward to meet the lightning bolt.
Check our video blog on Lightning Protection in the beautiful Brookgreen Gardens.