Reported September 2008

What is Lightning?: Lightning is a form of static electricity. We experience static electricity every time we drag our feet on carpet and then touch a conducting surface, like a metal doorknob. The shuffling causes our bodies to pick up extra electrons. Touching something with a positive charge, like metal, causes the electrons to "jump" across the small gap from our fingers to the object, and we experience a tiny electric shock. Similarly, lightning occurs because clouds become negatively charged as the water droplets inside rub up against each other during the natural process of evaporation and condensation, when moisture accumulates in the clouds. This charge seeks out something with a positive charge -- the ground, ideally -- and the lightning is the "spark" closing the gap between the two.

As more and more water droplets collide inside a cloud, the friction between them produces enough extra energy to knock off electrons. The ousted electrons gather at the lower portion of the cloud, giving it a negative charge. Eventually the charge becomes so intense that electrons on the earth's surface are repelled by the growing negative charge and burrow deeper into the earth. The earth's surface becomes positively charged, and hence very attractive to the negative charge accumulating in the bottom of the cloud. All that is needed is a conductive path between cloud and Earth, in the form of ionized air -- another byproduct of the collision process. When the two charges finally meet, current jumps between the earth and the cloud, and the result is lightning.

The American Mathematical Society, the Mathematical Association of America, the American Meteorological Society, the Institute of Electrical and Electronics Engineers, Inc., and the Institute for Operations Research and the Management Sciences contributed to the information contained in the TV portion of this report.

If you would like more information, please contact:

Vladimir A. Rakov, Ph.D.
University of Florida
(352) 392-4242
rakov@ece.ufl.edu

American Mathematical Society
http://www.ams.org

Mathematical Association of America
http://www.maa.org

American Meteorological Society
http://www.ametsoc.org

Institute of Electrical and Electronics Engineers, Inc. IEEE-USA
http://www.ieee.org

Institute for Operations Research and the Management Sciences
Barry List
(443) 757-3560
barry.list@informs.org