Lightning is visible almost instantly because light moves much faster than sound. That's why we see lightning before hearing thunder during a storm.
During a storm, clouds become electrified due to the friction between ice crystals and water droplets that violently swirl inside. This friction separates electric charges: the bottom of the clouds becomes predominantly negative, and the top mainly positive. The result is a strong electric tension between clouds or between a cloud and the ground. As soon as the tension becomes sufficient, it cracks in the form of a lightning bolt, a powerful electric discharge that suddenly heats the air all around. This air, at over 25,000 degrees Celsius, rapidly and violently expands, creating a sound wave: thunder.
Light is an electromagnetic wave that can propagate through a vacuum without any issue, whereas sound requires a material medium, such as air, water, or a solid, to travel. This is why sound cannot move through empty space, while sunlight easily reaches us through the vacuum of space. Another major difference is speed. Light travels at about 300,000 kilometers per second, which makes it almost instantaneous to our eyes when a lightning bolt flashes in the sky. Sound, on the other hand, is much slower, at around 340 meters per second (in air at room temperature). This slowness perfectly explains why thunder reaches our ears several seconds after we see the bright flash.
When a lightning bolt strikes, what we perceive first is its light, as it travels at nearly 300,000 kilometers per second (which is almost instantaneous on our scale). The sound, on the other hand, is much slower — about 340 meters per second, almost a million times slower. As a result, even though they are created at the same moment, the light rushes into your eyes right away, while the sound takes time to travel the distance to your ears. The farther away you are, the greater this delay becomes. It's a bit like when you see someone kick a ball in the distance: you instantly see the foot strike, but you hear the noise with a noticeable delay.
To estimate how far away a thunderstorm is, simply count the number of seconds between a flash of lightning and the sound of thunder. Since sound travels at about 340 meters per second, you just need to multiply that number of seconds by 340. For example, if 3 seconds pass, the storm is approximately 1 km away. This simple method gives you a quick idea of how close or far the danger is. However, be careful; if the delay shortens, the storm is getting closer: it's better to stay cautious!
Every day, around 8 million lightning strikes hit our planet, which amounts to about a hundred impacts every second worldwide!
Lightning can follow several paths: between cloud and ground, between two clouds, or even within a single cloud.
Aircraft are designed to handle lightning strikes and are hit on average once a year without damage, thanks to their conductive structure.
The temperature inside a lightning strike can reach up to 30,000 degrees Celsius, which is about 5 times hotter than the surface of the Sun!
The method of counting the seconds between a lightning flash and its thunder remains an estimation. While a one-second delay corresponds to approximately 340 meters, this technique is only approximate due to local variations in the speed of sound, primarily influenced by temperature and humidity in the air.
Not necessarily, but lightning has a natural tendency to strike tall and pointed objects, as they create the most electrically favorable path to the ground. Nevertheless, lightning can strike in several different places depending on the weather conditions.
Unlike landline phones, mobile devices generally do not pose an increased risk of being struck by lightning. However, it is strongly recommended not to use or hold plugged-in devices during a thunderstorm.
Thunderstorms are often triggered by intense heat, which causes warm, moist air masses to rise rapidly into the atmosphere. In summer, these conditions are typically met, thereby increasing the frequency and intensity of thunderstorms.
This impression generally comes from the speed at which sound travels. As the storm moves closer to your position, the interval between seeing the lightning and hearing the thunder decreases, creating the impression that it is approaching quickly.
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