How Do You Calculate The Distance From Lightning?
• Watch the sky for a flash of lightning. • Count the number of seconds until you hear thunder. If you have a watch with a second hand or a digital watch that has seconds, begin timing as soon as you see the lightning and stop as soon as you hear the thunder start. If you don’t have a watch, do your best to count the seconds accurately. Say “One one thousand, two one thousand etc.” in your mind for each second. • Divide the number of seconds by 5 to calculate the distance in miles (or divide by 3 for kilometers). In other words if you counted 18 seconds from when you saw the lightning, the strike was 3.6 miles (6 kilometers) from your location. The delay between when you see lightning and when you hear thunder occurs because sound travels much, much more slowly than light. Sound travels through air at about 1100-1200 feet (330-350 meters) per second (depending on altitude, relative humidity, pressure, etc.), which is a little more than one mile per five seconds (one kilometer per three