SHOCK THERAPY

Enlarge Image Image Gallery Lightning strikes in Norse myth (far left), movie myth (left) and in the legends of our country.

Protecting your home and loved ones from lightning

LIGHTNING, LIKE OTHER FORMS OF violent weather, can be humbling. By comparison, human efforts at destruction seem paltry. Just one thunderstorm, for example, may release the energy equivalent of 100 nuclear bombs. And at any given time, there are around 1,800 of these storms at work around the world.

With all the discretion of a maniac with a machine gun, the clouds over our planet let loose at the ground some 100 times per second. On the authority of up to a billion volts and 200,000 amperes—generating temperatures four times higher than those on the surface of the sun—a single lightning bolt can leap across 90 miles of air. All this it does as a routine part of its job, which is to stabilize the 300,000-volt potential that exists between the ground and the electrosphere.

Lightning is feared as much for its unpredictability as for its power. About 500 North Americans will be struck by lightning this year. But, for mostly inexplicable reasons, two-thirds will survive the experience. Two thousand buildings will burn, and $30 million worth of timber will be destroyed. But many houses and trees will be struck and show no damage. Perhaps the best illustration of lightning's capricious nature is the true story of the man who survived being hit by lightning only to die when the ambulance rushing him to the hospital was zapped, causing the driver to lose control and careen off the road.

The Risk of Being Struck

There are no surefire measures that will entirely protect you or your property from lightning. But there are ways to reduce personal risk and to provide a modicum of protection for buildings.

Probably the most effective, if not the most practical, move would be simply to head north—or south. The majority of lightning strikes take place between 30N and 30S latitudes. Hot spots to flee in the United States include Florida (about 100 lightning-days per year in the center of the state), the Rocky Mountain Front Range of New Mexico and Colorado (about 60 days per year, with as many as 20 concentrated in midsummer), and the lower parts of Texas, Louisiana, Mississippi, Georgia and South Carolina (60 or more days per year). If you're not quite ready to pull up stakes to avoid lightning, though, take solace in the plight of the people of Java, who worry through an average of 223 thunderstorm-days each year.

After geography comes topography. Risk is greatest where you or your home are most exposed, offering a lightning flash the easiest (shortest) possible path to ground itself. Mountaintops are the worst locations, with hillsides, flat land and valleys offering progressively more protection. However, along with the exposure presented by the lay of the land, you also need to consider the height of your home compared to nearby objects. For example, close trees that extend well above the peak of your roof are more likely to take a strike than the building. (This, of course, won't be much comfort if the fried tree falls on the house.)