LIGHTNING! IT CAN FRY YOU!

In Greek mythology, Zeus hurled devastating lightning bolts at errant gods and mortals from the top of Mt. Olympus. Today, we no longer believe lightning ZeusÕ anger causes lightning, but we still regard it with awe and fear. In East Texas, itÕs lightning season again and we ought to know something about it. In the United States, it kills about 100 people each year.

Lightning is a giant spark that can leap as far as five miles from a cloud to the ground or from cloud to cloud. The boltÕs tremendous surge of electricity blasts through the air at between 60,000 and 90,000 miles per second, instantly heating the air to as much as 50,000 degrees Fahrenheit (three times hotter than the sunÕs surface) compressing it into a shock wave that races outward at 1100 feet per second and is heard as a crash of thunder. Although the average lightning bolt lasts only 1/10,000 of a second, it packs energy as high as 150 million volts and 125,000 amps. Multiply the volts times the amps and youÕll find out how many watts of power are produced by that brief flash. ItÕs enough electricity to run a 100-watt light bulb for three months! By comparison, an arc welder uses 250-400 amps to weld steel. A homeÕs whole electrical system is normally rated at only 200 amps and current higher than a mere 20 thousandths of an amp can stop your heart!

A lightning bolt is caused by negative charges in clouds and positive charges on the ground or in other clouds. When these charge differences become great enough, a negative Òstepped leaderÓ starts down from the cloud and a positive ionized path moves up from the ground. They meet and in the tiniest fraction of a second, the main change flashes from the ground up. Lightning has no hesitation about striking twice and sometimes ten or twelve separate discharges flicker rapidly along a single path to the same unlucky target.

You can learn how far away the strike is by counting the number of seconds between the flash and the boom and multiplying by eleven hundred (the speed of sound). For example, when you see a flash and five seconds later hear the thunder, the bolt was about 5,500 feet away, or a little over a mile.

Lightning Safety

At the first sign of a thunderstorm you should:

1. Leave exposed places like baseball diamonds, golf courses and lakes.
2. Come down from high ground. You do not want to be the tallest thing in the area.
3. Avoid taking shelter under or near isolated trees or in small metal picnic shelters. They make great lightning rods.
4. Resist the urge to use phones unless theyÕre wireless. Lightning sometimes travels down phone lines and kills people.
5. Turn off and disconnect all computer equipment including the phone line to the modem.
6. DonÕt use appliances and power tools connected to home or office power lines.
7. Avoid metal or wire fences. They can deliver a fatal shock for miles.
8. Stay away from open windows.
9. Get into a car or truck. Even if lightning strikes it, the current will pass through the vehicle body, leap around the tires from the metal wheels and pass harmlessly into the ground. (The insulation of the tires has nothing to do with your safety.)
10. If you cannot get to a safe area, crouch down, keeping your feet together and cover your ears to protect them from sound damage. Do NOT lie down flat on the ground.

LightningÕs Varied Forms and Signs

Usually, lightning appears as straight, jagged or forked bolts, but youÕve probably also heard of Òheat lightning,Ó which has nothing to do with heat. ItÕs lightning flickering in clouds too far away to hear thunder. ÒSheet lightningÓ is merely flashes inside a cloud that cause it to light up.

Ball lightning is quite rare and poorly understood. Varying from the size of an orange to larger than a basketball, it may drift slowly down from a cloud after a lightning strike, roll along the ground, or as in one case, drift through an open door. Some have come down chimneys and through window screens. Lasting only three to five seconds, they emit a sizzling sound and the smell of hot metal or ozone, then silently disappear or collapse with a loud bang.

Sometimes lightning gives us a warning. As a Park Ranger at Grand Canyon National Park, I was on an observation point at the canyon rim when a thunderstorm moved into the area. A young girl standing near me began to giggle as her fine, light hair started to crackle and stand straight out from her head. We immediately left the area and although nothing more happened, this static display was an indicator that a lightning strike was a real and dangerous possibility.

NatureÕs electricity sometimes appears as a humming, flickering, bluish corona called St. ElmoÕs Fire on pointed objects like antennas, aircraft wing tips, cattle horns, tree tops and even peopleÕs heads. (They say it tingles but doesnÕt hurt or cause injury!) Mountaineers have mentioned hearing the Òhumming of the beesÓ and seeing St. ElmoÕs Fire on trees and sharp pointed rocks just before a lightning strike. This strange, visible phenomenon means that high energy electricity is present and lightning may follow without warning. Whether itÕs a humming sound, static in your hair, St. ElmoÕs Fire or simply thunder, donÕt hang around to see whatÕs going to happen. Get to a safe place. Otherwise, you may make an ash out of yourself!