How to calculate the distance from you to the lightning bolt flash.
In reality and with some scientific accuracy, we can estimate the distance between the flash of the lightning bolt and when the thunder is sounded.
Sound travels through air at “the speed of sound.” But of course! Officially, the speed of sound is 1,087 feet per second (or 331.3 meters per second) in dry air at 32 degrees Fahrenheit (or 0 degrees Celsius). Raise the temperature to something like 82 degrees F (28 degrees C) the speed of sound is now 346 meters per second. Suffice it to say that the warmer the temperature, the faster sound travels, modified by other contributing factors such as humidity in the air.
As you can see, the math required to come up with an “accurate” distance can be daunting… so, we simplify the math by “rounding off”. Let’s use something like 1,200 feet per second (or 350 meters per second) as the reasonable numbers to describe the speed of sound. So, using our rounded off figures, sound travels 1 mile in roughly 5 seconds (or 1 kilometer (1,000 meters) in roughly 3 seconds)). For you math buffs, this method translates to 1.1363636 miles — we’ll call it “one mile”.
So, how do we do it when we see the lightning flash?
Start counting the seconds between the flash and the thunder. Count (saying this out loud) “…one thousand one, one thousand two, one thousand three, one thousand four…….. ” etc. Don’t race when reciting the numbers… use “normal” speech speed.
When you see the flash of a lightning bolt, you start counting the seconds, stopping when the thunder stops sounding off. You then divide the result, the quantity of seconds, by FIVE (5) to see how far away, in miles, the lightning struck.
For example: If it takes 10 seconds for the thunder to roll in after you saw the lightning flash, the lightning struck about 2 miles away. And, the thunder would have been quite loud given the short distance between your ears and the lightning flash.
By the way, lightning does not have to hit the ground or a building to make the thunder sound off. Watch for lightning that seems to go no where but between clouds. These events will not give you the “distance” you seek. So, look for lightning strikes that seem to hit the ground where you can learn just how far away it might have hit.
Want to help your children be much less afraid of these thunderous events? Teach ‘em to count the seconds, then divide the results to learn the distance. Have them log several “hits” for comparison, creating a kind of contest between several children. Using an “area” map showing where you are located, mark the “hits” in the general direction of the strike.
Taking photos of a lightning strike can make for an interesting “show ‘n tell” project. With today’s digital cameras, including cell phones, taking shots of the lightning strike in the darkened sky can be challenging even for pro photographers. But, learning how to successfully take some shots of lightning and be able to publish them or print them for an amateur photographer’s display would certainly be an item the child can store in their own albums giving the child super bragging rights for decades to come.
Here’s a challenge for you adults and soon to become adults:
I’ll foster the contention that the kids will outshine their adult counterparts both in the observations of the lightning strikes and in the accuracy of the math needed for the project.