Have you ever been outside and wondered what the temperature was, but had no thermometer?  Did you know that you can tell the current temperature by the rate at which a cricket is chirping?  It's true.  Just count the number of chirps you hear for 15 seconds.

Enter the number of chirps in 15 seconds:

The temperature is:

Just in case you might not have a laptop with a cellular internet uplink available on your next backpacking trip, there's a very simple formula for calculating these values.

For the Fahrenheit temperature take the number of chirps in 15 seconds and add 40 to it.  For example, if you counted 10 chirps, the temperature is 50 degrees (10 + 40 = 50).  Nifty, huh?

The Celsius calculation is a little more complicated, and you may find a calculator useful.  As such, we've broken it out into steps.

1. Get the Fahrenheit temperature as detailed above.

2. Subtract 32 from it.

3. Divide the results by 2. (or multiply by 0.55556 if you really want to get dorky - Warning-  converting Fahrenheit to Celsius in the wilderness is pretty dorky to begin with)

So let's say again that our Fahrenheit temp is 50 degrees.  

1. 50 degrees 

2. 50 - 32 = 18

3. 18 / 2 = 9  (or for the intellectually inclined out there: 18 x 0.55556 = 10)

So 10 chirps in a 15 second interval means that it's 10 degrees Celsius.