Thunderstorm calculator: find lightning distance description

This application can calculate distance how far away a thunderstorm is.
Tap Lightning button when you see the lightning, then tap Thunder button when you hear it. The application will calculate the distance of a thunderstorm from your current location. The accuracy depends on how fast you are. How it works? Sound velocity is about one kilometer per 3 seconds. Application calculate time between the lightning and thunder (you mark them using buttons) and than using sound speed distance is calculated.