Just count the number of seconds from the time you see a flash until you hear thunder. A few seconds later, you hear a sharp click or loud crack from lightning channels a little farther away, and several tens of seconds later the thunder from the most distant part of a flash has quieted to low frequency rumbling.īecause light travels through the air roughly a million times faster than sound does, you can use thunder to estimate the distance to lightning. Very close to lightning, the first thunder you hear is from the closest channels,which produce a tearing sound, because that thunder contains high frequencies. Thunder can be heard up to 25 miles away from the lightning discharge, but the frequency of the sound changes with distance from the lightning channels that produce it, because higher frequencies are more quickly absorbed by the air. The huge pressure in the initial outward shock wave decreases rapidly with increasing distance and within ten yards or so has become small enough to be perceived as the sound we call thunder. What causes thunder? Lightning causes thunder! Energy from a lightning channel heats the air briefly to around 50,000 degrees Fahrenheit, much hotter than the surface of the sun. What we do: Read more about NSSL's lightning research here. It can be seen in volcanic eruptions, extremely intense forest fires, surface nuclear detonations, heavy snowstorms, in large hurricanes, and obviously, thunderstorms. Lightning is one of the oldest observed natural phenomena on earth. Lightning can occur between opposite charges within the thunderstorm cloud (intra-cloud lightning) or between opposite charges in the cloud and on the ground (cloud-to-ground lightning). The flash of lightning temporarily equalizes the charged regions in the atmosphere until the opposite charges build up again. When the opposite charges build up enough, this insulating capacity of the air breaks down and there is a rapid discharge of electricity that we know as lightning. In the early stages of development, air acts as an insulator between the positive and negative charges in the cloud and between the cloud and the ground. Watch on the NOAA Weather Partners YouTube Channel» What is lightning? Lightning is a giant spark of electricity in the atmosphere between clouds, the air, or the ground. You don't want to get struck by the next flash of lightning.Weather Briefly: Lightning. Remember, if you can hear thunder, chances are that you're within striking distance of the storm. Keep in mind that you should be in a safe place while counting. If you count the number of seconds between the flash of lightning and the sound of thunder, and then divide by 5, you'll get the distance in miles to the lightning: 5 seconds = 1 mile, 15 seconds = 3 miles, 0 seconds = very close. Since you see lightning immediately and it takes the sound of thunder about 5 seconds to travel a mile, you can calculate the distance between you and the lightning. The loud boom that you sometimes hear is created by the main lightning channel as it reaches the ground. If the thunder sounds more like a rumble, the lightning was at least several miles away. Typically, a sharp crack or click will indicate that the lightning channel passed nearby. As you continue to listen, you'll hear the sound created from the portions of the channel farther and farther away. When you listen to thunder, you'll first hear the thunder created by that portion of the lightning channel that is nearest you. This rapid expansion and contraction creates the sound wave that we hear as thunder.Īlthough a lightning discharge usually strikes just one spot on the ground, it travels many miles through the air. Immediately after the flash, the air cools and contracts quickly. The temperature of the air in the lightning channel may reach as high as 50,000 degrees Fahrenheit, 5 times hotter than the surface of the sun. The lightning discharge heats the air rapidly and causes it to expand. Thunder is created when lightning passes through the air. The sound of thunder should serve as a warning to anyone outside that they are within striking distance of the storm and need to get to a safe place immediately! Thunder is the sound caused by a nearby flash of lightning and can be heard for a distance of only about 10 miles from the lightning strike.
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