"And when you hear that thunder..."

Lightning puts on a super-charged light show. — b_napper/Creative Commons

Getting struck by lightning is something we think will never happen to us, but that kind of thinking can get you killed. There’s awesome power in those thunderbolts and lightning strikes more often and more powerfully than you might think.

At any given moment, scientists estimate there are some 2,000 thunderstorms boiling above the globe, discharging 100 lighting strikes per second. This may actually have something to do with the electrical currents in the ionosphere that deliver fair weather somewhere else — usually to a place where you are not or at a time you can use it least, as on a workday Monday.

Every year lighting strikes about 400 Americans, killing between 80 and 100 of them outright and leaving many of the survivors with life-long disabilities. That’s a relatively small tally, given the fact that lightning annually makes contact with 30 million points on the ground in the lower 48 states, a statistic produced by a nationwide lightning detection network.

The average bolt packs a walloping 200 million volts, more than enough for a direct hit to kill instantly. But a direct strike isn’t the only danger.

True to its own imperative — finding the path of least resistance — these giant sparks of static electricity can strike you after bouncing off metal fences, trees, party tents and flagpoles, or while traveling up to 60 feet through the ground from the point of contact. Current also can travel through wiring, plumbing, air conditioning ductwork and telephone lines. In fact, many of those injured indirectly were talking on the phone during thunderstorms.

Lightning develops when the electrical charges within a storm cloud are wrenched apart. The process is poorly understood, but scientists believe that rain drops attract a negative charge and, being heavier than air, sink to the bottom of the cloud. Meanwhile, strong updrafts thrust the positive charge to the top of the cloud.

As the storm builds and clouds lower, negative charges on the groundward side descend in herky-jerky steps of 150 feet. As these “stepped leaders” (invisible to us) approach the earth, positive charges on the ground or on towers or trees can stream up toward them. When the opposing charges meet, the circuit is completed and a luminous return stroke is discharged — this stroke is what we see as a lightning flash. Don’t blink, by the way. The whole sequence takes less than half a second.

Tall objects are more vulnerable because they lift positive charges higher off the ground and closer to the storm cloud. The old adage that one should not seek shelter in a thunderstorm under isolated tall trees is sound advice on three counts. For one thing, that towering tree can attract a stepped leader, triggering a lighting flash.

Another danger has to do with the path of least resistance. Bearing in mind that water is an excellent electrical conductor, consider the fact that the tree has a moisture content of 20 percent, while yours is 65 percent. Can you guess where the charge is headed? Finally, even if you avoid getting hit directly or on the bounce, an impacted tree can shatter, catch fire or fall.

Shattered: A tree struck by lightning. — timo_w2s/Creative Commons

Weird fact: We’ve only learned recently that lightning goes up into the stratosphere as well as down to the ground and sideways between clouds. These discharges, detected by space shuttle crews and NASA satellites, take strange forms and were quickly given fanciful names. The “red sprites” look like the stems of carrots, the “blue jets” like streaks of light with the ends flared like trumpets, and the “green elves” are glowing blobs that look like amoebas or jellyfish. Go figure.

Back on earth, you rarely get fury without sound. Thunder is a byproduct of the shock wave produced by the passage of those superheated electrical discharges we call lightning. And sound, traveling one-fifth of a mile per second, always follows light, which is zipping along briskly at 186,000 miles per second.

I always believed that the seconds between the flash and the bang equaled the number of miles between you and the storm. Not so. You must count the seconds and divide by five. A 10-second interval means the storm is not 10 miles away, but two, and a lot closer than you thought.

Another weird fact: Lightning can strike as much as 10 miles from the place where a storm is dumping rain, and can come quite literally as a bolt out of the blue.

A 22-year-old East Windsor man was killed on the beach at Island Beach State Park in 2001 in hazy sunshine on a hot July day. There was no thunder heard, no warning at all. Keep a weather eye on the horizon when storms might be brewing, and remember that most lighting injuries occur just before and just after the brunt of a storm arrives, rather than when rain is actually falling overhead.

The worst place to be in a thunderstorm is in the open, as on sporting fields, bare mountain tops, beaches or farmland. Contrary to what many think, only five percent of injuries occur on the golf course; 27 percent took place in open areas, 14 percent under trees and eight percent on or near water, another hazardous location.

The safest place to be is in an enclosed building with plumbing and wiring to conduct the charge to the ground — pavilions, dugouts and tents don’t count. A hardtop car with the windows rolled up is a good second choice, but avoid contact with metal parts. Forget the convertible, and step away from metal bikes or motorcycles.

Let’s say you are caught out with no shelter, not even a ditch or depression to lower yourself into. If the hair on your arms rises as when you pass it near an operating television screen or your hear crackling noises preceding a lighting strike, you are in imminent danger. Adopt the pose: Put your feet together, crouch down as low as possible, cover your ears to protect against rupture and close your eyes. Move to a better location as soon as possible.

An ounce of prevention is ever worth a pound of cure. Be aware of the forecast if you plan to be outdoors, and follow the 30/30 rule: Seek appropriate shelter if the interval between lightning and thunder is less than 30 seconds, and wait for 30 minutes after the last rumble before heading back outside.

Bonus: Check out this real-time map of lightning strikes around the globe.