If you have a digital or analog watch, begin timing as soon as you see the lightning and stop as soon as you hear the thunder. If you don’t have a watch, do your best to count the seconds accurately. Say "One one thousand, two one thousand..." in your mind as you count. Sound travels one mile every five seconds and one kilometer every three seconds. Therefore, if you want to find out how far you are from lightning, divide the number of seconds by 5 if you want the answer in miles and divide it by 3 if you want the answer in kilometers. The delay between when you see lightning and when you hear thunder occurs because sound travels much more slowly than light. Here's what you do:  Let's say you counted 18 seconds. To find your distance from the lightning in miles, divide 18 by 5 to get 3.6 miles. To find your distance from the lightning in kilometers, divide 18 by 3 to get 6 kilometers. Though you won't be able to get a completely accurate result because the weather may vary in temperature and humidity, which will slightly affect the speed of sound, this is a good way to estimate how far you are from the lightning. Sound travels at a speed of about 344 meters, or 1,129 feet, per second. To calculate your distance from the lightning in meters, just round 344 down to 340 and multiply the number of seconds by 340. To calculate your distance from the lightning in feet, just round 1,129 up to 1130 and multiply the number of seconds by 1130. Here's how you do it: Let's say you counted 3 seconds. Multiply that number by 340 to get your distance in meters. 3 x 340 = 1020 meters. Multiply that number by 1130 to get your distance in feet. 3 x 1130 = 3,390 feet.
شاهد وميض البرق في السماء. عد عدد الثواني حتى تسمع الرعد. احسب المسافة من مكان البرق بالميل أو الكيلومتر. احسب مسافتك من البرق بالمتر أو القدم.