Science & Culture Corner
LIGHTNING
Recently, on a mountain camping trip, I sat with several high school students to watch the lightning flashes within a fast moving thunderstorm. It was quite entertaining, but even more so in the form of questions posed by the students. In some cases I was well surprised to learn how little high school students are taught about this amazing phenomenon.
As first demonstrated by Ben Franklin, lightning is electrical flow not unlike what goes on inside an ordinary flashlight (but at an obviously more intense level). Electricity's nature is to flow from a charge at point A to a different charge at point B until the charges are equalized. As in a flashlight, and just as a river flows between mountains (rather than over them), it seeks the path of least resistance.
My favorite question was why light normally tries to travel in a straight line while lightning seems always to travel in a jagged line. The answer is that lightning is not light. The light you see is merely a by-product of the electric flow, as is the sound of thunder, which usually follows. Unlike light, lightening changes its course to use the clouds, air, trees, etc., having the least electrical resistance.
Another good one concerned some lightening which travels more slowly down to the earth. Actually, it is always instantaneous, as its natural unfettered speed is that of light (300,000 kps). When it appears slower it is a case of continuing its travel after having paused. It does this because either its flow has changed the charge at its point B, its voltage increased by something affecting point A, or the resistance has changed. Further, it does not always strike the ground, but may strike from the ground to the clouds, or from cloud to cloud.
A third question was about how thick the rubber in car tires has to be to protect someone in a car. The answer is that any thickness won't help. It is only a myth. Lightning cares not of car tires. Besides, it is perfectly capable of crossing through the air between the car and the earth. Most cars though (Corvettes excluded) are quite safe. The ferrous content around the car's cabin sets up electromagnetic field that deters lightning.
All over the world many people die each year from lightning (see JT Oct. 1998 issue). To protect yourself, remember that it seeks the most convenient connection between earth and sky. Its favorite connection would be a gold pipe rising up out of a lake. While this is obviously not a common occurrence, sitting in a canoe in a lake (during a storm) is nearly the same thing.
SIDEBAR
PROTECT YOURSELF IN A STORM
1- Don't be the tallest
object in the area.
2- Don't be under the tallest object in the area.
3- Don't be talking via the tallest object (telephone wires or ham radio) in the area.
That is, stay off the telephone.
4- Boating is ok if the boat has a lightning rod, but otherwise, no boating or swimming.
5- Get to lower ground if outside- don't be on top of a hill.
6- Do not work outdoors with any tools or other objects made of ferrous metals, i.e.,
hammer, shovel, axe.
7- If indoors, open as many windows as practical. Lightning is often accompanied by
low-pressure winds, which, if extreme enough, can explode a home.
by Angel
Stephens
angel_stephens@hotmail.com
EDITOR'S NOTE-
Angel Stephens as a Harvard student studied physics at the Harvard Smithsonian and writes today on the subjects of physical science and anthropology for numerous publications.
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