Weather Imagery

The best way to answer this is to explain the concept behind a lightning rod, the unpredictability of a lightning strike and what happens when the lightning hits the lightning rod. Lightning rods do not attract lightning until it is very close to the rod, and the best way to explain this is probably through an example.

A simple lightning rod is nothing more than a conductive piece of metal about 3 feet in length that sits atop the highest point on a house. Attached to this piece of metal is a thick copper wire that runs down the side of the house and attaches to a pipe which is driven several feet into the earth. That’s it.

A lightning bolt is far more complex. The point to understand is, a lightning bolt doesn’t know what it’s going to strike when it first starts to form. The kind of lightning we are worried about is called a cloud-to-ground strike which starts high in the clouds. On average a cloud-to-ground lightning bolt produces about 1,000,000 kW or about 50,000 amps, which is a lot! Ok, here we go. As more and more positive charge builds on the ground beneath the storm, more and more negative charge builds in the lower part of the cloud. As the charge continues to build, so does the attraction between the positively and negatively charged particles. The only thing stopping the electric current from flowing is air, which happens to be a very good insulator. This allows an immense amount of charge to build up.

As the charge builds, the air between the cloud and the ground starts to ionize (this part is invisible). This is done in small little paths, step-by-step, zig-zagging all about (this is why lightning looks the way it does and isn’t a straight line). Once it gets to within 100′ of the ground something weird happens. Objects on the ground begin throwing up “streamers”. These are like little fingers that shoot upwards about 50 feet. The first streamer to touch a step leader coming down from the cloud above will complete the circuit and a huge surge of electricity will flow (this is the part we see as lightning). Understanding that lightning doesn’t know at 50,000 feet what it’s going to strike is the key to this whole paragraph. It’s not until the last 100 feet or so that things are in danger of being struck.

Now, say the lightning bolt is making its way down to the ground and it’s heading right for your house. Your rooftop or satellite dish (or maybe both) throw up a streamer. If that streamer makes contact with the main channel first, well, that’s bad. That means the lightning bolt is going to hit your house and cause a great amount of damage. So regardless of whether you have a lightning rod or not, your house is going to get struck. But, what if you did have a lightning rod on your house and it threw up the streamer instead of your rooftop or satellite dish? The step leader would then stand a much greater chance of hitting the streamer coming up from the lightning rod. The electric current when then pass through the lightning rod, down through the copper wire and into the Earth. This is what you want! Your house (and your wallet) would not suffer any damage and life goes on as normal.

So, the lightning rod attached to your roof doesn’t really attract the lightning any more so than your roof or satellite dish do. If the lightning is close enough, your house was going to be hit either way. But assuming you do have a lightning rod, the odds of lightning striking the rod instead of some other part of your house are greatly increased.

Other Lightning Myths

• Is Ball Lightning Real?
• Can Lightning Crash an Airplane?
• Can Lightning Be Used As a Source of Power?
• Can Lightning Strike the Same Place Twice?
• Do Car Tires Protect Me From Lightning?
• Can Lightning Strike Me Inside My House?