Have you ever wondered how far away from you a thunderstorm is? In that case, ThunderTimer is what you have been looking for ThunderTimer calculates how far away a lightning is based on the difference between the speed of light and the speed of sound. nnThunderTimer will also give an indication of whether the thunderstorm is moving away or towards you. ThunderTimer supports both U.S. and metric units for measurement. ThunderTimer can of course be used to measure similar events, like fireworks and others. Additionally, further development goals are to use the integrated compass in IPhone 3GS together with GPS localization to pinpoint the location of the lightling on a map. Another further enhancement is to log the measured distances.