When I was young, I had a fear of thunderstorms – astraphobia as it’s called. I got this from my mother. No, not genetically, but she was scared of them, so I was, too. In time, though, my love for all things weather took over. As a budding meteorologist, I started to enjoy these raw displays of nature. Over the years, I’ve done some strange things during thunderstorms – I’ve played golf through them, and I also played tennis through one. But, so much for my eccentricities.
For “normal” folks, I would recommend a healthy respect for thunderstorms, something between hiding in a closet and sitting on your roof holding a metal golf club. The good news is that lightning kills very few people. In 2013, lightning killed 23 people in the United States – that was a record-low number. The worse news is that you can probably multiply that number by 10 to get the number of people injured by lightning – and some of them have been left with permanent disabilities.
Continuing along that line, thunderstorms occur in every state. Even Alaska gets many storms in its brief summer. The farther south you go, the more storms you get, and they can even occur in the winter. (Rarely in the North can you get lightning in the winter – the famed “thundersnow.”)
It is estimated that in one year, lightning hits the ground 25 million times somewhere in the U.S. Florida typically leads the country in lightning strikes and casualties. Southwest Florida is considered the lightning capital of the U.S. with some locations getting more than 100 thunderstorms a year. And although storms are most common in the late afternoon, they can occur at any time of the day.
Lightning is an electrical discharge in the atmosphere. Interestingly, it is a byproduct of those puffy cumulus clouds so common in the summer. As the cloud grows and produces liquid water and ice high up, an electrical field is generated. Lightning is common within the clouds themselves, but it’s the cloud-to-ground bolts we have to worry about. And, as you may have heard, electricity is flowing both down from the cloud and up from the ground. If these flows connect, then we get the full-blown lightning bolt. Obviously, people who are working outside are at a greater risk of getting hit by lightning. This is true for the home gardener, and it is especially true for the farmer or rancher who is out in open fields, often too busy to keep constant track of the weather.
So, how do you know if thunderstorms are possible? First, check the weather forecast, which will give you a probability of a thunderstorm occurring at your location. But it is impossible to know exactly where thunderstorms will develop in advance. Also, there are no “official” warnings for lightning like we have for tornadoes. If thunderstorms are forecast, the threat of lightning is inferred. Before you head outside, check the local weather radar. Televisions, computers, even phone apps let you do this. When you look at a weather radar display, you’ll see different colors – blue, green, yellow, red, etc. Those colors correspond to how hard it is raining.
Notice I’ve said nothing about lightning. Radar does not detect lightning. Why am I talking about radar then? Thunderstorms usually produce heavy rain, so places that are getting very heavy rains are more likely to be getting lightning, too. On that radar display, look out for yellows and especially reds, which are most likely thunderstorms. You can see how far away they are, and if you watch over time, you can determine if they’re coming toward you and at what speed.
Instruments exist that can actually detect lightning strikes, and there are lightning detection networks, which again are available online. These can be dialed in locally as well, and are often now shown by your hometown TV meteorologist. You can also purchase your own lightning detectors, which range from relatively inexpensive hand-held units to elaborate systems costing thousands of dollars.
Conveniently, thunderstorms send out their own lightning warning signals. We call this thunder. Thunder is the sound made when lightning heats the air, causing it to expand rapidly. A close lightning strike makes a loud crack or explosion. This tends to scare people, but if you heard it, it missed you! More distant strikes produce rumbling thunder with the sound waves bouncing and reflecting.
And the old rule does work: If you see lightning, count five seconds, and if you then hear the clap from the strike, the lightning was 1 mile away. If you count to 15 before you hear it, the lightning strike was 3 miles away. This formula has to do with the speed of light, which is almost
instantaneously fast, and the speed of sound, which is much slower. By the way, lightning bolts have been known to strike as far as 10 miles away from their parent thunderstorms. And lightning always produces thunder.
What about “heat lightning” you ask? Heat lightning is produced by a storm so distant that even though you can see the lightning bolt, the sound waves it produced have dissipated before they reach you.
Out of harm’s way
So what do you do if a thunderstorm is getting close? Go inside. And I don’t mean a metal shed or an outhouse. Even if struck by lightning, a home or building will protect you. How close is too close? The National Weather Service (NWS) recommends the “30-Second Rule”: If you count 30 seconds or less after you see lightning until you hear thunder, it’s time to seek shelter. How long do you stay inside? The NWS recommends 30 minutes after you’ve heard the last rumble of thunder.
You’re also safe in a car. That’s a sedan, not a convertible. Open-cab vehicles afford no protection from lightning. And this certainly includes sitting on tractors and horses. If you’re outside and can’t get in, don’t seek shelter under a tree. Lightning seeks the highest object, and electricity can jump and run underground. So don’t get anywhere near that tree. Also keep away from metal fences, and stay away from water.
If you’re outside in the open, crouch down. You don’t want to be that highest object. But don’t lie down – remember that electricity running through the ground I just mentioned. Crouching minimizes your exposure.
When disaster strikes
What do you do if someone is hit by lightning and is just lying there? First, there is no danger; all the electricity has gone. Often a lightning victim has gone into cardiac and/or respiratory arrest. If the person is not breathing, administer CPR. This brings up another lightning safety rule: If you are caught outside with other people, spread out. If one of you is hit, then others can help.
Again, a house or other substantial structure is a safe place to ride out a storm. There are, however, a few rules to follow even when inside. If your house is hit by lightning, the electrical current will likely follow the wiring in your house. So, stay off the phone, at least those with ground lines. People on phones have been killed by lightning. Cell phones should be safe. Also, stay away from electrical appliances. Avoid anything with plumbing like sinks or showers. The pipes can conduct electricity. Avoid windows or outside doors, and stay off the porch. In terms of protecting what’s in your house, if possible, unplug all electrical devices. At the very least, turn off everything you can, especially that computer and high-dollar television. Surge protectors also offer some protection.
Thousands of homes are hit by lightning every year. Total damage runs in the hundreds of millions of dollars. So what about protecting your home? Well, lightning rods have come a long way since Ben Franklin invented them sometime around 1750. Franklin’s idea was to divert the lightning bolts away from structures by attracting them to nearby tall metal poles. The electricity could then be shunted safely into the ground. Today, lightning protection systems use much smaller metal rods, called air terminals, placed strategically across the roof of the structure. The goal is not to attract lighting, but rather divert a bolt that was destined to hit the home or building. Once a bolt is intercepted, the electricity is sent along thick stands of woven wire that connect all of the rods. The wire leads to a long metal grounding rod buried deep in the soil. From here, the electrical charge can be dissipated safely into the ground. You can check your local listings for certified providers in your area. You can install a system yourself or have a general contractor do it, but proper installation is critical to ensure protection.
Now for some good news: Thunderstorms bring life-supporting rains, especially in the summer. Without these rains, we’d have no gardens or farms. They’re replenishing the ground water supplies, too. And the threat from lightning can be minimized by following the rules outlined above. So find a safe location, and enjoy one of nature’s greatest shows!
For 30-plus years, Ed Brotak taught thousands of college students about the weather and helped hundreds of them pursue a career in meteorology. He lives in Asheville, North Carolina, with his wife (also a meteorologist) and his two daughters (who vow never to be “weather weenies”). He still goes outside when he hears thunder.