NEWTON: Tornados and Radio Frequencies
 
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Name: James
Status: educator
Grade: 6-8
Location: GA
Country: USA
Date: Fall 2013


Question:
Does a tornado generate a radio frequency, and if it does what frequency? According to some research, analog televisions tuned to Channel 2 can detect tornado and thunderstorms. Is there some validity to this?


Replies:
Hi James,

Thanks for the question. I am unaware of any research precedent in this area. In principle, a tornado could generate electromagnetic waves and these waves could possibly be in the radio frequency range. Here is a possible scenario: An object picks up a static electrical charge, perhaps by contact friction. The tornado whips this object around and causes it to undergo an acceleration. A charged object that accelerates will radiate electromagnetic waves. The frequency of the radiated electromagnetic waves (energy) could be in the radio frequency range. This explanation is a possible, but not terribly probably scenario that could explain electromagnetic waves emanating from a tornado. For a much more thorough discussion on electromagnetic waves and how they are generated, I recommend reading J.D. Jackson's "Classical Electrodynamics" book.

I hope this helps. Thanks Jeff Grell


Hi James,

Lightning is an electrical impulse, which is an extremely fast rising voltage spike, and a powerful one at that. It can be shown using a mathematical analysis known as a Fourier Transform that ideal electrical impulses generate signals at every frequency. Much smaller impulses can be generated in the laboratory, and if you watch the signal with an instrument called a spectrum analyzer you can see for yourself that this is true.

Note that I referred to "ideal" impulses. In the real world there are no ideal impulses, but lightning comes pretty close. As such it will come close to producing what the Fourier analysis predicts, but it will not be a perfect match. An easy way to see for yourself is to turn on an AM radio during a thunderstorm. It will not matter where you tune it, you will hear a burst of static whenever lightening strikes.

Now to at last address your question, you could use an analog television tuned to any channel you like to see that a storm is in the area. I think televisions do a better job filtering out that sort of distortion, though, and you would get a better indication from the AM radio. I cannot think of any reason a TV tuned to Channel 2 would be especially useful in this case. Lacking lightning I would not expect a tornado alone to produce much RF energy at all.

J. Gardner


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