Light on Lightning! Danger!Sound moves about 1,000 feet per second through air. To find out how far away the storm is, start counting “1 one-thousand, 2 one-thousand…” when you see a flash. Five counts, or five seconds, equals about one mile. But lightning bolts don’t come just from the center of the storm. To see the dangers of a “bolt from the blue,” place the little humanoid about five or six miles from the storm. Wait, and watch! The shadow of sound Light and sound both refract (changes direction) when their waves move into a medium of different density. Glass lenses work because of the different density of air and glass. This is harder to see with sound waves, but it can happen near a thunderstorm, where air temperature and density can both change quickly. When air near the ground is warmer than air higher up, sound will travel faster through the denser air near the ground, and sound waves will refract, as you can see around mile seven. During the Civil War, these “acoustical shadows” caused artillery that could be seen in the distance to be inaudible on parts of the battlefield.