Electronstatics

Lightning and Lightning Rods by Scott Zhu

Ligthning

Lightning is being created by:


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.

Function of lightning rod

The main functions of the lightning rod is to reduce the likelihood of a lightning strike and, if a strike occurs, to conduct the charge safely to the ground. The lightning rod reduce the likelihood of the lightning strike, because the charges streaming between the cloud and the lightning rod tend to neutralize each other, and this may be enough to prevent lightning from striking. But if the strike do occur, then the lightning would be more likely to hit the rod than the building that the rod is attached to, and be conducted to the ground safely, because lightning takes the path of least resistance between a cloud and the ground, and lightning rod would always be higher than the building, and the lightning will strike the rod.
Lightning Rods Part 1