Dolbear's Law
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Dolbear's Law states the relationship between the ambient temperature and the rate at which crickets chirp. It was formulated by Amos Dolbear and published in 1897 in an article called "The Cricket as a Thermometer". Dolbear expressed the relationship as the following formula which provides a way to estimate the temperature TF in degrees Fahrenheit from the number of chirps per minute N:
This formula is accurate to within a degree or so when applied to the chirping of the snowy tree cricket. Reformulated to give the temperature in degrees Celsius, it is:
The above formulae are expressed in terms of integers in order to make them easier to remember — they aren't intended to be exact.
The chirping of the more common field cricket is not as reliably correlated to temperature — its chirping rate varies depending on other factors such as age and mating success.
