The Physics
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Electric Current through a Lightning Bolt

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Bibliographic Entry Result
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Zim, Burnett, & Paul E. Lehr. Weather. New York: Golden Books, 1987: 99. "A lightning discharge is incredibly powerful--up to 30 million volts at 100,000 amperes--but is of very short duration; hence lightning cannot be harnessed or used." 100 kA
"Lightning." Encyclopedia Britannica. Chicago: Encyclopedia Britannica, 1989: 351. "A typical lightning flash involves a potential difference between cloud and ground of several hundred million volts, with peak currents on the order of 20,000 amperes." 20 kA
Posey, Carl A. The Living Earth Book of Wind and Weather. Pleasantville, NJ: Reader's Digest, 1994: 91. "The amounts of energy behind these… transmissions are staggering, ranging from about 3,000 to 200,000 amperes with currents in the millions of volts." 3–200 kA
Chandler, T. J. The Air Around Us. Garden City, NY: Natural History Press, 1969: 95. "The net result is equal to a constant upward current of about 200 amperes. More powerful still is the current of approximately 1000 amperes produced by a "point discharge"from trees, buildings, and lightning conductors. 1.2 kA
Mallette, Vincent. Everything You Always Wanted To Know about Lightning — But Were Too Shocked to Ask (yeah, we know!) a.k.a. Algorithm, Inc. Lightning Page (lightning is your friend). "An individual bolt can pack several hundred million volts at 10,000 amperes, one trillion watts, briefly burning up more electrical power than is being used in the entire United States. Monsters of one billion volts and over 100,000 amperes are not unknown." 10–100 kA

The electric current in a lightning bolt is measured in amperes (A). An ampere is defined as the constant current which, if maintained in two straight parallel conductors of infinite length, with negligible cross sections, and placed one meter apart in a vacuum, will produce between these conductors a force equal to 2 × 10−2 newton per meter of length.

A single lightning bolt is extremely powerful; measured in thousands and hundred thousands of amperes (kiloamps or kA). All of my sources on lightning basically differed from each other, ranging from a value of 1,200 amperes to about 200,000 amperes, but because in all cases the results I found were approximations or generalizations, some sources were closer in value than others.

I believe there are two reasons why all of my sources contained different information. First, all lightning bolts are different sizes and intensities due to different atmospheric conditions and other factors, therefore each bolt differs in its value of electric current. The currents are not the same for each bolt. Second, since a lightning strike is of such a short duration (up to 18 strikes a second!), it is nearly impossible to capture one bolt long enough to take precise measurements. There isn't an instrument advanced enough to take such a reading accurately.

Also, I noticed that generally speaking, the older the source, the lower the current. I believe this is because the instruments used today are more advanced than the instruments used almost 20 years ago. These new instruments have determined that lightning bolts are more powerful than originally thought, hence the discrepancies in my sources.

Brooke Haramija -- 1997