June 30, 2008

Lessons on lightning for the Fourth

BY ROY MITCHELL

You may not have noticed an obscure event last week. It received far less coverage in the press than Cedar Bluff Liberty Day, off-season Alabama football, or even Jamie Lynn Spears' baby. Nestled in media obscurity behind more glamorous headlines was the fact that the last full week in June was Lightning Safety Week.

Though the odds of sustaining a lightning injury are statistically quite slim, lightning threats sweep over the skies of Cherokee County with every summer thunderstorm. As the outdoor merriment of a holiday weekend fast approaches, a review of lightning safety is appropriate.

Meteorologist James Spann with ABC 33-40 contacted The Post with some key thoughts about lightning.

“It doesn't have to be raining to be hit by lightning,” Spann said via email from his office in Birmingham.” Bolts from a storm anvil can be miles ahead of the rain.”

Spann also said the time to go inside to avoid danger is immediately after the first rumble of thunder. He said summer afternoon thunderstorms usually pack the most lightning; a thousand ground strokes are typical with a single storm, he said.
“If you are outdoors, avoid water,” Spann cautioned. “Avoid the high ground. Avoid open spaces. Avoid all metal objects including electric wires, fences, machinery, motors, power tools, etc.”

He also suggested that even though people are safe from lightning while indoors, it is still wise to consider unplugging expensive electronic devices.

The National Geographic website lists even more stringent indoor precautions, including not talking on a corded phone during a thunderstorm. The site also warns against lying on the concrete floor of a garage as it likely contains reinforcing steel bars.

Before donning holiday attire on the water or at any other Fourth of July outdoor event, understand that being outdoors on Independence Day weekend in Alabama may include a higher degree of lightning risk.

Consider the following research: The Southeast includes four of the top eight states in the nation in the number of lightning-strike deaths from 1990 to 2003, and Alabama is one of those four (www.lightningsafety.com). According to National Geographic the Fourth of July “is historically one of the most deadly times of the year for lightning in the U.S.”

Not only is lightning a threat to human safety, electrical strikes from a thunderstorm threaten standing structures. Centre Fire Chief, Kevin Ware estimated that lightning causes five to seven house fires a year in Cherokee County.

“Any kind of metal in or on a roof can be a conductor and the electricity will jump from one thing to the next,” he said.

“When lightning hits the ground, it spreads out along the surface and first few inches of the ground in increasing circles of energy called 'ground current',” read another lightning-themed website. “If it contacts a fence or a water pipe or wire entering a house it can be transmitted for quite a distance and cause injury to persons near these paths.”

Ware said he witnessed that type of electrical transfer at a recent house fire. He said the fire began when lightning struck a tree in the resident's yard. The current ran down the trunk and into the ground, where the voltage spread to a nearby sprinkler system. The electrical current followed the sprinkler system through the yard and under the garage, where the current ignited the house.

Ware said lightning traveling through a ground conductor sometimes leaves a distinctive signature. “A dirt path is dug up like a mole would do.”

A few years back, while Ware's family was building a house in eastern Cherokee County, lightning struck the roof. Without any wiring to serve as a ground, the lightning ran to the metal parts of a window and blew the several two-by-fours across the house.

The traveling current actually tossed bricks from the base of the house out into the yard, one of which ended up across the road, about 150 feet away.