Storm Tracker is a free iPhone app developed by DOUBLE U s.r.o. It falls under the Lifestyle category and specifically the Weather subcategory. This app allows users to calculate the distance of lightning and determine how far away a storm is.

Using the difference between the speed of light and sound, Storm Tracker provides a simple and effective way to measure the distance of lightning strikes. When you see the lightning, tap a button in the app, and then tap again when you hear the thunder. The app will then calculate the time difference between the two events and provide an estimate of the distance of the storm.

With Storm Tracker, users can stay informed about the proximity of storms and make informed decisions about their safety. It's a handy tool for outdoor enthusiasts, travelers, or anyone who wants to keep track of approaching storms.