How should you behave during a thunderstorm?
It's starting to storm, darker clouds are gathering in the sky, and the sky above doesn't bode well. Especially in summer – on very hot and humid days – lightning and thunder are not uncommon. Stefan Zender from the weather portal wetterkontor.de knows what to do during a thunderstorm.
Colder air masses push over the warm, humid air layer at ground level. The sun further heats the air layer near the ground. Warm air shoots upward, the water vapor condenses, and forms enormous cumulus clouds. These thunderstorm clouds can reach heights of up to 19 kilometers. Ice particles form within the cloud, which quickly develop into hailstones. Ice particles and hailstones rub against each other. This friction creates electrical charges. At the edge of the stratosphere, the ice shield typical of a thunderstorm cloud forms.
Different voltages now exist at the top and bottom of the clouds, and at the ground level, with their charges becoming increasingly stronger. Lightning is ultimately a "short circuit" within a thundercloud or between a thundercloud and its surroundings.
Thunderstorms are primarily announced by the clouds. As cumulus clouds become larger and more powerful, and the edges at the top of the clouds become frayed, showers and thunderstorms could occur.
Another sign is high humidity and high temperatures, and of course, thunder or lightning if a thunderstorm is approaching. Then it's time to seek shelter.
You should avoid hills, lakes, rivers, trees, and poles. Unless you can seek shelter in a house or vehicle, it's best to find a hollow, crouch down, place your feet together, and wrap your arms around your legs.
This minimizes the surface area for lightning to strike. It's also important that the depression or hollow isn't damp. If there's standing water in the depression, voltage can easily be transmitted through the ground. Lightning always seeks the easiest path. This includes the path over water and moisture – because of their good conductivity.
Anyone paddling on a lake, just like swimmers or divers, must reach the safe shoreline. Water conducts lightning even 100 meters away from the point of strike. Effective lightning protection is practically impossible on boats: Therefore, open boats have no place on the water during a thunderstorm.
If a thunderstorm is brewing or approaching, you should generally avoid being outdoors. You should leave the sports field as quickly as possible, and a soccer match or training session, for example, should be stopped immediately – because lightning strikes on the field are also extremely dangerous.
The voltage from a lightning strike in close proximity can actually spread through the water supply system. Even though the risk of electric shock from tap water is relatively low compared to other hazards, it's best to postpone showering. This also applies to any other activities involving contact with tap water.
If lightning strikes near a house, the voltage can also jump to a nearby power or telephone line and be transmitted all the way to the house. Therefore, particularly expensive or sensitive electronics should be disconnected from the power supply unless there is internal lightning protection.
Making phone calls with a cell phone or a cordless landline phone is safe, but the base station can be damaged by a power surge. To be on the safe side, unplug all electrical devices.
During a thunderstorm, you should not use an umbrella: it represents the highest elevation.
In the event of a lightning strike, the car acts like a Faraday cage, a completely enclosed metal grid. If a car is struck by lightning, a strong charge is created only on the surface. The entire voltage is discharged through the exterior of the car into the ground. No electric field is created inside the vehicle. However, the windows should be closed.
Cyclists and motorcyclists should definitely stop their ride during a thunderstorm. So, dismount, keep a distance of at least three meters from the vehicle, and crouch down, preferably on asphalt, or even better, seek shelter in a building.
Good to know: If three seconds pass between a visible flash of lightning and a clap of thunder, the thunderstorm is less than a kilometer away. The danger isn't over until you haven't heard any thunder for half an hour.
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