Lightning and Lightning Rods by Scott Zhu
1. Air currents in the storm cloud cause charge separation. The top of the cloud becomes positively charged, and the bottom becomes negatively charged.
2. Negative charges on the bottom of the cloud induce a positive charge on the ground below the cloud by repelling negative charges in the ground.
3. When the bottom of the cloud has accumulated enough negative charges, the attraction of the positive charges below causes electrons in the bottom of the cloud to move toward the ground.
4. When the electrons get close to the ground, they attract positive ions that surge upward, completing the connection between the cloud and the ground. This is the spark you see as a lightning flash.
Danger of lightning
The lightning carries an extremely large electric current, which leaves the tall buildings and the trees vulnerable. Because lightning takes the path of least resistance between a cloud and the ground, usually striking the highest object in an area. On average a lightning bolt carries 3 million volts per meter, which is highly destructive. In Canada, one thirds of the forest fires were all caused by the lightning strikes, and about 10 death per year. Unfortunately, the lightning strikes could not be prevented, but lightning rods could lower the possibility and damage the lightning strikes could produce.