If it cracks and flashes: what to do in a thunderstorm

In bright sunshine you decide to go for a little run in the evening. "But that's humid," you think to yourself on the way out. Less than an hour later, you're racing with the dark thunderclouds. Because one thing is certain: the risk of being struck by lightning is small, but you shouldn't risk anything.

Sometimes you can actually watch how the cloud mountain towers higher and higher on top of each other. If the rising moisture reaches such cold layers that small ice crystals form, these fall back down and are whirled around together with the moisture. That creates tension. Similar to a battery, two poles form. Above plus, below minus. If the electrical voltage becomes too great due to the friction of the layers of air, then it discharges to earth – with your lightning bolt.

How far away is the storm?

If you are out and about and hoping to get home quickly, you can easily calculate how far away the thunderstorm is.

The thunder is caused by the sudden expansion of the air layers around the lightning channel. If the thunderstorm is still a few kilometers away, we will see the lightning, but only hear the thunder later - the sound of the thunder is just slower than the light of the lightning.

With a quick glance at the clock and counting the seconds before the sound of thunder hits you after the lightning strike, you can determine the storm's distance. Multiply the counted seconds by 340, the approximate speed of sound in meters per second, and you know how far away the thunderstorm is now.

What to do?

If your legs can't carry you as fast as the black wall is approaching, then it's best to seek shelter. In a closed building or car. But what if you are alone in the fields and fields? Follow grandpa's advice "You should give way to the oaks, you should look for the beeches"? Better not! Forests or free-standing trees should be avoided not only because of the risk of lightning strikes, but also because of the frequent stormy winds and possible falling branches. You should also stay away from other elevations of all kinds, such as poles or fences. Because lightning often chooses the highest point in the area to discharge.

So: it is best to make it small in a depression! Making small means squatting down and putting your feet close together. In the unlikely event of a nearby lightning strike, no dangerous voltage can develop between the feet - the so-called step voltage. By the way, this is also dangerous if you still try to walk home. This step voltage also occurs meters away from the direct impact and creates a dangerous current through the body.

Listen to the lifeguard

No question arises when training in the outdoor pool. Even if it is uncomfortable when the lifeguard pulls out the whistle in the middle of the swimming set. Due to light poles, stainless steel pools and fences, the outdoor pool is a dangerous place during a thunderstorm. The current can also spread particularly well in water.

But what if you are out on the lake? The following is even more important here than for any other training session: Before you start, it is better to look at the sky twice and, together with the weather report, assess whether there is a risk of a thunderstorm.