The following interesting information comes from New Scientist magazine.

Playing Cricket

QUESTION
A friend of mine assures me you can tell the temperature by listening to the chirping of crickets. Is this true and, if so, how?

ANSWER
There is an old rule that the ambient temperature in degrees Fahrenheit is equal to the number of cricket chirps in 15 seconds plus 40. The ambient temperature in Celsius is roughly equal to the number of cricket chirps in 8 seconds plus 5.

Thus, if a cricket is heard to chirp 112 times in one minute, the temperature is approximately 68 °F or 20 °C.

Experiments that have been carried out on the snowy tree cricket (Oecanthus fultoni) suggest that the chirp rate is regulated by the rate of one or more metabolic reactions in the cricket. These experimental results are consistent with an exponential dependence on the cricket's absolute temperature.

This type of behaviour is described by the equation that was deduced by Swedish chemist Svante August Arrhenius in 1889 to explain the relationship between chemical reaction rates and temperature.
The rule described above, then, is a linear approximation to the exponential dependence and is usually good to within a degree or two over the range of temperatures at which crickets chirp.

ROBERT HOPKINS
Houston, Texas

ANOTHER ANSWER
It has been observed that the average frequency of chirping of a snowy tree cricket is 100 per minute at 17.3 °C, 126 per minute at 20.3 °C and 178 per minute at 25 °C. If a graph of this data is drawn, it is clear that as the temperature increases, so does the chirping of the crickets.

Therefore, the following formula can be applied to the data: the temperature in degrees Fahrenheit equals 0.8 multiplied by the number of chirps in 15 seconds plus 42. This temperature can then be converted into Celsius by subtracting 32, multiplying by 5 and dividing by 9.

So yes, it is possible to calculate the temperature by listening to the chirping of crickets.

MICHAEL HADCROFT
Glasgow, Scotland

ANSWER
An Arrhenius plot for the chirping of crickets features on page 66 of To Light Such a Candle by Keith J. Laidler (Oxford University Press, 1998). Interesting biological applications of the Arrhenius law are discussed in the Journal of Chemical Education (p 343, vol 49).

EDITOR

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