How Lightning Works
The shocking truth

It’s thunderstorm season again in Oklahoma! While recently driving back home from an event, my husband, a friend and I were watching an intense lightning storm illuminate the night sky. After discussing how “cool” it was, I spontaneously blurted out, “Did you know lightning comes from the ground?”

Some questioning silence ensued, and I decided I had better brush up on my lightning facts before saying dogmatic things like that again. After researching for some time, I found out that lightning is quite the controversial subject. So, what follows is my best attempt at explaining the correct (yet simplified) way of how lightning occurs.

Lightning begins with static electricity. You may know it as the thing that zaps your siblings when you touch them after dragging your socked feet across the carpet. That’s basically what happens in clouds when a thunderstorm starts to form. Instead of socked feet dragging against the carpet, there are moisture molecules and ice crystals in the clouds that start rubbing together to form an electrical charge. They start to move faster and faster as they rub together. What happens next is called a chargeseparation.

Inside the storm cloud, there is fast moving air moving both up and down, called updrafts and downdrafts. The updrafts take small water droplets high up in the cloud, way above freezing levels. At the same time, the downdrafts move the hail and ice from the top of the storm down to the bottom. In the midst of all this turmoil, the ice and water droplets collide. Smashing into the ice causes the water to suddenly freeze, and ironically, heat is released. The heat makes the surface of the hail and ice a little bit warmer than everything else around it. This causes electrons (which are negatively charged) to be shaved off of the particles going upward, and they fall to the bottom of the cloud. What ensues is a cloud that has a positive charge on top and a negative charge on the bottom. Thus, you have a charge separation! In the middle of the cloud is an abundance of electricity just hanging out … literally.

For the purpose of simplifying this further, think of a thunderstorm cloud as a cream-filled cookie. The top cookie is all the positive charge, the bottom cookie is all the negative charge, and the cream in the middle is the electric field. The electricity starts growing and getting stronger as the thunderstorm grows in strength. While this is happening, another “cream-filled cookie” is forming between Earth’s surface and the bottom of the storm cloud. The ground ends up taking on a positive charge, while the bottom of the storm cloud is still negatively charged. This is what causes the dramatic flashes of lightning we are accustomed to.

The three main types of lightning are cloud-to-ground lightning, ground-to-cloud lightning and cloud-to-cloud lightning. Yes, technically lightning can originate from the ground, but that kind is rare. (I’m happy my spontaneous outburst wasn’t a total lie). Cloud-to-cloud lightning is the most common of all, making up 75-80 percent of all lightning. It’s the kind that you’ll see in the distance, with the clouds illuminating in repetitive flashes, or you just won’t see flashes at all. Cloud-to-ground lightning is the kind that we’re used to seeing, and it is generated naturally from the cloud, making its way down to earth. Let’s break down what all that means.

In cloud-to-ground lightning, a channel of negative charge (called a stepped leader) from the bottom of the cloud will start making its way downward towards earth. As it nears the surface, a channel of positive charge from the ground (called an upward leader) will reach up and meet it, usually travelling up tall things like trees and buildings. When the two connect, a much larger electrical current is formed, causing the loud, dramatic flash we know as lightning. The stepped leader never travels in a straight line, which gives lightning it’s zig-zagged form. Because of this, it doesn’t always mean that the tallest upward leader will connect with a stepped leader to form a lightning strike. In other words, there’s no way of knowing exactly where lightning will strike. And that’s why the tallest building or tree isn’t always the location of a strike.

A lightning bolt only takes a few thousandths of a second to crack through the air. When the lightning bolt is formed, a second stroke of lightning returns from the ground to the cloud. This return stroke is so hot that it raises the temperature of the air around it up to around 50,000 F°. For reference, that’s half the temperature of the surface of the sun (insert shocked face here). The dramatic rise in temperature also causes a rapid increase in air pressure, causing the air surrounding the heated air to compress. Once the air is done compressing, the pressure drops and it cools, causing it to contract back quickly. All of this happens within a very short amount of time, and the result is a shock wave complete with a loud, startling boom that can awake us out of our slumber.

While it’s easy to think thunder and lightning are two separate things, the truth is that you need one to get the other. There will always be thunder with lightning and vice versa. But sometimes it seems possible to hear thunder and not see lightning. Is that actually possible? Short answer: no. The sound of thunder can only travel up to 12 miles from the storm. So, it’s possible that you just see the storm but are so far away that you can’t hear the thunder. Alternatively, if you hear thunder but don’t see the lightning, it could be that it’s just cloud-to-cloud lightning, concealed within all the grayness.

Have you ever counted the seconds between the lightning flash and the sound of thunder? I used to do that, thinking the number equaled the number of miles the storm was away from me. Well, that turns out to be another half-truth. Sound travels much slower than light, so we usually see the flash of lightning before we hear the thunder. Sound travels around one mile for every 4.5 seconds while light travels at a startling 186,000 miles per second. The correct equation for calculating how far a storm away is as follows: Divide the number of seconds between the flash of lightning and the sound of thunder by five. So, if you see a flash and count to five Mississippi, the lightning is only one mile away.

Lightning can happen 50-100 times a second all around the world. If you’re located within the United States, Florida happens to be the best state to watch a lightning storm—it ranks as the highest of all the 50 states for lightning occurrence. While most lightning bolts are 2-3 miles long, they are only 2-3 centimeters wide (insert another shocked face here). The world record for the longest flash happened in 2020, with a lightning bolt stretching over 477 miles across three states—Mississippi, Louisiana and Texas!

What is even more stunning is how complex and intricate God’s mind is to create something like lightning. And then to think of everything else He created! I don’t think there are enough shocked faces to cover it all.

I’d like for it to go on the official record that it was thundering while I was writing this.