The light travels at 186,291 miles per second (~300,000 km/s), and speed of sound in dry air is equal to 0.21 - 0.22 miles per second (0.33-0.35 km/s), as it varies with the temperature. We can notice the lightning almost immediately even though the storm is far from us, but the thunder needs around 5 seconds to travel one mile and approximately 3 seconds to travel one kilometer. Thanks to this seven orders of magnitude difference in sound and light propagation, we can easily estimate the storm distance
