Winds, rainstorm and dark clouds may be signs of impending cloud to ground lightning.

Method for determining when a thunderstorm will arrive: When thunder is heard, the distance between its location and the lightning strike is determined by calculating the length of time between hearing and seeing lightning. Due to the fact that the speed of light is approximately one million times faster than the speed of sound, there will be a certain time difference between lightning and accompanying thunder. If there is a 5-second interval between seeing lightning and hearing thunder, it indicates that the lightning strike occurred about 1.5 kilometers away from oneself; If you hear thunder in just one second, which is the blink of an eye, it means that the lightning strike is located 300 meters near you.

When encountering thunderstorm weather, remember whether the time interval between hearing thunder and seeing lightning is getting longer or shorter, in order to determine whether the thunderstorm is gradually moving away or getting closer.