This application calculates the distance of a thunder storm by measuring the time between a lightning and the corresponding thunder. How to use: - When you see the lightning press the 'Lightning' button. - Wait until you hear the thunder and press the 'Thunder' button. - Tap the distance to toggle between metric and imperial units. - With the help of the history list you can see whether the storm comes closer and moves away. Background: The speed of light is much faster than the speed of sound