It’s safe to say that thunderstorm season has officially arrived in Iowa! The temperature and the humidity has been on a steady climb for the last couple of weeks (remember when we were making jokes about how cold it was?!?) and seasoned midwesterners can spot the ideal weather for a good thunderstorm from miles away!
I love thunderstorms! For some reason, they always prompt me to bake a batch of chocolate chips cookies whenever they roll through! (There’s nothing quite like watching the clouds roll in while you chow down on homemade cookie dough!) Unfortunately, my children do not share my affinity for thunderstorms, not even the promise of warm chocolate chip cookies can calm their nerves when the thunder starts booming and the lightening flashes!
Last week a quick thunderstorm rolled up in the middle of dinner. Instead of focusing on the scary booms and flashes I said to them “Did you know if you count the number of seconds between when you see the lightening and hear the thunder, you can estimate the distance the thunderstorm is from our house?” (P.S. Did you know that?)
The speed of sound through the air is approximately 340 meters per second, and the speed of light is approximately 300 million meters per second. Even though thunder claps and lightening flashes are happening at the same time, the difference in speed makes it seem as though the lightening is flashing before the thunder.
Using the relationship between distance, rate, and time we know that D = R*t, where D is distance, R is rate, and t is time. Since we have the rate of sound and light in meters and seconds, we’ll also report D and t in terms of meters and seconds.
Now, suppose you hear thunder approximately 5 seconds after you see a flash of lightening. If we use the relationship between distance, rate, and time we can substitute known values into the equation, which gives us D = 340*5 = 1700 (remember this is meters). 1700 meters is approximately 1 mile.
The next time a thunderstorm rolls up in your neighborhood, see if you can track how quickly its moving through the area. Keep a record of the length of time between lightening flashes and thunder rumbles. Can you tell when the storm is getting closer and farther away from you?
P.S. I got my facts and figures from two great sources: the National Weather Service and The Department of Physics at the University of Illinois Urbana Champaign.