The striking facts behind lightning

Few natural phenomena hold the fascination — or the danger — of lightning. A bolt of lightning packs a powerful punch — a spark of electricity that arcs from the clouds to a tree, a building, or a person, flash-heating the air around it to temperatures hotter than the surface of the sun. If that makes lightning sound dangerous, it is. But a little knowledge can help you to stay safe when a storm rolls in.

WHAT CAUSES IT?

Lightning is produced by the same thing that creates sparks when you shuffle across a wool carpet and touch a doorknob, or when you brush a cat: a buildup of static electricity. In fact, a spark is precisely what a lightning bolt is, but on a much larger scale.

Opposite charges build up, either within a thunderhead, or in the cloud and on the Earth’s surface. When opposing charges build up high enough, lightning breaks through the insulating air and strikes the ground.

When lightning reaches the Earth’s surface, it most often strikes tall objects such as skyscrapers, mountaintops, trees, or utility towers. And though it’s not particularly drawn toward metal, metal is highly conductive when it is struck. When a person is the tallest thing in the landscape — say, on a golf course, in the middle of an open farm field, at a building jobsite — or even standing too close to a lightning target such as a tree, they can become a target, too.

WHAT ARE MY CHANCES OF GETTING STRUCK?

The Centers for Disease Control and Prevention (CDC), says your chances are low, with an average of 28 people dying from lightning strikes each year. This represents about 10 percent of victims. But though it’s possible to survive a close encounter with lightning — about 400 people in the U.S. do, each year — odds are you won’t escape serious consequences. About 70 percent of survivors suffer serious long-term effects, including severe burns, permanent brain damage, memory loss, and personality changes.

That said, you can better your odds by staying weather-aware during your outdoor hours, particularly when you’re pursuing leisure activities like fishing, hiking, or soccer, during which six in 10 lightning deaths occur.

HOW DO I STAY OUT OF HARM’S WAY?

Because the storms that produce lightning can be fast moving, particularly in open country, it can be difficult to judge how far off the storm is, but know that lightning can have a long reach, striking five to 10 miles out from a storm’s center. Use the 30/30 rule to gauge the threat. If you can’t count to at least 30 seconds after seeing lightning, it’s time to go inside and stay there until 30 minutes after hearing the last clap of thunder.

Open structures such as gazebos, porches, or the space beneath athletic bleachers don’t provide adequate protection. “Inside” means inside a home, office, or any enclosed building. In a pinch, a hard-topped car with the windows rolled up will do. If you’re in a home or office equipped with landlines, stay off the phone, as lightning can follow the wires, delivering a deadly jolt through the handset.

If you’re stuck outside as the clouds gather, with no shelter nearby, the National Oceanic and Atmospheric Administration (NOAA) advises to keep moving toward shelter and offers these “last resort” tips and more.

Immediately get off elevated areas such as hills, mountain ridges or peaks.
Never lie flat on the ground.
Never shelter under an isolated tree.
Never use a cliff or rocky overhang for shelter.
Stay away from objects that conduct electricity (barbed wire fences, power lines, windmills, etc.)
Immediately get out and away from ponds, lakes, and other bodies of water.

Sources: NOAA National Severe Storms Laboratory; National Geographic; FEMA

The information included here was obtained from sources believed to be reliable, however Grinnell Mutual Reinsurance Company and its employees make no guarantee of results and assume no liability in connection with any training, materials, suggestions, or information provided. It is the user’s responsibility to confirm compliance with any applicable local, state, or federal regulations. Information obtained from or via Grinnell Mutual Reinsurance Company should not be used as the basis for legal advice and should be confirmed with alternative sources.

4/2024