Lightning, the biggest chunk of pure electricity you can find, can be as perplexing as it is powerful. I learned it can leave us in the dark even before a strike. How can that be?
We’ve all played with magnets as children; odds are, you can remember putting one atop a table and moving it with a hidden magnet beneath. It illustrates the beautiful concept of a magnetic field — the region of magnetic influence surrounding an object. Electricity behaves in the same way, shrouded in an electromagnetic field.
Lightning, and all electricity for that matter, emits something called a “sferic.” Also known as a radio atmospheric signal, this is essentially the electromagnetic “shock wave” that ripples out in all directions immediately following a lightning strike. Close to the strike, this wavelet can cause erratic behavior in electronic devices by changing or enhancing the electric field.
Wayne Verno, a meteorologist at the Weather Channel in Atlanta, noticed some bizarre electrical activity in response to a thunderstorm on Monday. “We had a lightning strike to my neighborhood,” he said. “Just an incredible flash and powerful blast, and lightning data confirmed a direct strike.” But it was what happened immediately beforehand that caught his attention. “We lost power about a second and a half before the strike,” Verno said.
Could it be an eerie coincidence? Doubtful. The buildup of charge immediately before a nearby strike can cause power surges through the electrical grid. As free electrons move toward or away from the object that will be struck, they can exert a push/pull force on neighboring electrons — including those within your home’s wiring. If too many electrons move at once, they can blow a fuse — and knock out power.
Oddities are the norm when it comes to lightning striking homes. Strange electrical effects have been known to persist weeks or even months after taking a strike. Whether it be fried wires or problems with an alarm system, strange things can happen — and they do.
Sometimes, the gathering of charge preceding a strike can have wacky impacts, too. Verno is not alone. Many who have been close to lightning strikes report hearing static on their AM radios or walkie-talkies. Lightning emits a variety of frequencies but is most prominent at lower frequencies — meaning that effects are about 10 times greater to AM radio signals than to FM.
Even household appliances or handheld devices can “feel” when charges congregate. If you’ve ever been on a phone when lightning strikes, you may have heard this firsthand. A “pop” or burst of static accompanies the lightning immediately because the sferic propagates out from the strike at the speed of light — 100,000 times faster than associated thunder. This effect is the same whether you’re on a cellphone or landline — although you should not be using a corded phone during a thunderstorm, in case lightning travels through the circuitry.
I experienced the unique effects of a sferic myself. On May 2, I was riding up the H.E. Bailey Turnpike east of Lawton, Okla. As I was traveling east exiting a severe thunderstorm complex that would later spawn 17 tornadoes, lightning struck a nearby wind turbine. In replaying my dashcam footage, I noticed an unusual static sound coincident with the strike on tape — exactly the signature that the spark’s sferic briefly tripped up the current in my camera.
Lightning tracking employs this knowledge to our advantage. With a spattering of stations across the country “listening” for this radio fingerprint of lightning, it’s easy to do. When a probe “hears” a lightning strike, it can estimate the distance; by overlapping the known distances from three separate stations, software can pinpoint to within a few hundred meters the location of a strike.
Of course, if you’re Verno, you can detect lightning the old-fashioned way. After all, if lightning strikes your block, you’re going to know it.