Weather Station

Bolts from the Sky

by John Matthews

Lightning is actually static electricity. Static electricity is very much like the sparks you get when you walk across a carpet and touch something. However, Nature creates much more static electricity than all the rugs and carpets in the world combined.

Lightning forms when rain falls through clouds. As rain droplets fall, they tug electrons down through the clouds with them. Electrons are the tiny parts of an atom that have negative electrical charges. Nature likes to maintain a balance. So, when electrons get pulled out of place, Nature wants to put them back. That is exactly what lightning does.

Rain drops pull down electrons. But their proton partners get left behind in the upper part of a cloud. Protons are the tiny parts of an atom with a positive electrical charge. Protons and electrons are attracted to one another, just like magnets.

Lightning occurs when lonely electrons seek out nearby protons to recreate balance. Those protons might be resting at the top of another cloud. They can also form along the ground under the cloud. When protons are pulled from another cloud, the result you see is cloud to cloud lightning. But when the protons are pulled up from somewhere on the ground, the result is a lightning strike.

Well, not really. Lightning does not actually "strike" the ground. It stops about 50 feet above the ground. When downward flowing electrons meet upward flowing protons, they complete an electrical circuit. That circuit is much like the connection that forms when you plug in a CD player to an electric outlet and turn on the switch.

Lightning is actually a gigantic flow of electrons through the circuit that is completed in the air. On the ground, the protons closest to the downward flowing electrons will be pulled upward to complete the circuit. Those protons might be part of a tree, or part of a person standing in the middle of a golf course fairway.

Protons are drawn upward from the highest point closest to the electrons. That is why a person should never stand in a field or hide beneath a tree during a thunderstorm.

If you were the highest point closest to the flowing electrons in search of positive partners, the protons inside your body would begin to flow upward. Your hair, which contains protons, would stand straight up on end as those protons reach skyward. About 50 microseconds later—before you could even blink your eye—the circuit would be completed and you would be electrocuted.

So what is thunder?