Physics

You Can Tell The Temperature From Cricket Chirps, Thanks To Dolbear's Law

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Physicist Amos Emerson Dolbear is most famous for a small report he published in an 1897 issue of the American Naturalist that included these words: "The rate of [a cricket's] chirp seems to be entirely determined by temperature and this to such a degree that one may easily compute the temperature when the number of chirps per minute is known." This came to be known as Dolbear's Law.

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Why It's Awesome

Although Dolbear laid legal claim to the invention of the telephone (which the Supreme Court dismissed) and developed the wireless telegraphy system that eventually became the radio (which we attribute to Guglielmo Marconi), this bizarre scientific law about cricket chirps is the only contribution that bears his name. Which perhaps wouldn't make him thrilled, but we think the law is surprisingly handy. Ever wake up in the morning and wonder what the weather is like outside, but feel too lazy to look it up? With Dolbear's Law, you don't even have to open your eyes. That law is as follows:

Degrees Fahrenheit = 50 + (chirps per minute - 40)/4

Smart Graphic

Why It Works

All cold-blooded creatures, crickets included, follow the Arrhenius equation, which states that the rate of a chemical reaction depends on the surrounding temperature. Muscle contractions, like those that let a cricket chirp, happen via chemical reactions. So the colder it is outside, the slower the chemical reactions in a cricket's muscles, and the less frequent its chirps. When it's hotter outside, a cricket chirps more frequently. And you thought crickets were only good for keeping you up at night.

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