Cricketometer: If you listen, crickets will tell you about weather

There is a lot of weather lore about animals and weather.

There are groundhogs like Punxatawney Phil. There’s the Wolly Bear. And squirrel nests?

The truth about animal weather lore is there isn’t much science to back up accuracy claims. Punataweney Phil’s forecast accuracy is only about 39 percent in more than 100 years.

But there’s one critter that pretty good track record of giving us some metrics on current weather.

Cue the crickets. If you listen, they’ll tell you about the weather.

Cricket chirps

So, what is a cricket chirp? It’s the sound they make by scarping the rough edges on their wings together. And it features a shiny new science word.

Stridulation.

Scientific American explains.

How do crickets make their distinctive chirp? They use a process called stridulation, where special body parts are rubbed together to make a noise. Generally, only male crickets do this; there’s a special structure on the tops of their wings, called a scraper. When they want to make their sound, they raise their wings to a 45-degree angle and draw the scraper of one wing across wrinkles on the underside of the other wing, called a file. It’s somewhat like running your finger along the teeth of a comb.

Audio thermometer

There’s an easy way to tell the temperature by counting cricket chirps. Again, here’s the formula from Scientific American.

Count how many chirps the cricket makes in 14 seconds. How many? Write this number down.

Do this two more times, counting how many chirps the cricket makes in two more 14-second intervals. Write these numbers down. How close were the numbers to one another?

Average the number of chirps in the 14-second intervals.

Add 40 to the average number of chirps in 14 seconds.

The resulting number gives you the approximate air temperature. You can also try counting the number of chirps in 15 seconds and adding 37.

Most sources I follow suggest the crickets are usually accurate to within a couple of degrees.

How crickets react to temperature

So why are crickets so good at estimating temperatures?

It turns out the bodies of these thousands of mini thermometers in your neighborhood are temperature sensitive.

How is a cricket’s chirp related to temperature? Crickets, like all living things, have many chemical reactions going on inside their bodies, such as reactions that allow muscles to contract to produce chirping. Crickets, like all insects, are cold-blooded and take on the temperature of their surroundings. This affects how quickly these chemical muscle reactions can occur. Specifically, a formula called the Arrhenius equation describes the activation, or threshold, energy required to make these reactions occur. As the temperature rises, it becomes easier to reach a certain activation energy, thereby allowing chemical reactions, such as the ones that allow a cricket to chirp, to occur more rapidly. Conversely, as the temperature falls, the reaction rates slow, causing the chirping to diminish along with it.

So as our heatwave ramps up this week your neighborhood crickets will be busy. If you listen, they’ll do a pretty good job of telling you what the current temperature is.

High temperature forecasts Tuesday and Wednesday

Twin Cities National Weather Service

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