A lightning bolt is about the diameter of a quarter or half-dollar.
IStock/Andrew Cribb
It starts with hydrometeors …
Everybody knows lightning is a giant discharge of electricity, but how does that electricity actually build up in a cloud? Meteorologists believe that as ice particles (called hydrometeors) in a cloud break apart, the heavier particles tend to gain a negative charge and collect near the bottom of the cloud. Meanwhile the lighter particles gain a positive charge and rise to the top of the cloud. The separation of the positive and negative charges creates tremendous electrical potential in the cloud itself and between the cloud and the earth.
Then there’s a hole in the air…
“Think of the air between the cloud and the ground as electrical insulation,” says meteorologist Jeff Lutz. The electrical charge in the cloud can build to the point where it can break down that insulation. “The air gets a hole in it, somewhat like a vacuum,” Lutz says. A negatively charged streamer of energy heads down the path of the “hole” in steps of about 50 meters each, and when it reaches to about 50 meters above the earth, it attracts a positively charged streamer from the ground to meet it. Once the connection is made, current goes back and forth through the channel two to four times, generally, and this is the lightning bolt. A lightning bolt is typically about the diameter of a quarter or half-dollar.
And things get really hot …
A lightning bolt heats the air to 30,000 to 50,000 degrees Fahrenheit, which is three to five times hotter than the surface of the sun. Thunder results from the super-rapid heating and expansion of the air, and from the air rushing back to fill the vacuum created by the bolt.
Yes, there is upside-down lightning …
Sometimes a really tall structure like a radio tower can initiate the lightning bolt, so the bolt steps from the ground to the cloud, and the lightning branches point upward.
You’re safe in a car, sort of …
But not because of rubber tires. When lightning hits your car, the body channels the electricity around you and to the ground, so the car is electrified. If you are touching the car’s metal, you can get shocked.