Why do I feel better in thunderstorms

News topic of the day

Today, Thursday, it's that time again, a thunderstorm is imminent. And as is so often the case, the thunderstorms will not be evenly distributed across the country. Individual regions get strong thunderstorms, in the others almost nothing happens. Many a thunderstorm fan like to lament that it never "crashes" at their location. But is that also true?

In Germany there are definitely areas where thunderstorms tend to occur (see the graph on the average annual lightning density in Germany 1996 - 2005, to be found on the right under the heading "Topic of the day" under [more]). This includes all mountain regions. There, the air masses are forcibly lifted when the flow is flowing through the mountains and the upward movement that is always present in thunderclouds is increased in this way.

This can be seen well in summer, when cumulus clouds can already be seen over the mountains, but it is still cloud-free all around. Since there are more mountains in the south of Germany than in the north, the thunderstorms there are also more numerous. In addition, humid and warmer air masses often find their way to the south of Germany than to the north, which also promotes the formation of thunderstorms. Nevertheless, thunderstorms occur everywhere in Germany.

The impression that thunderstorms always pass a certain location can arise quickly, but in the vast majority of cases it can also be explained well. The "backdrop effect" is mostly responsible for this fact.

The "backdrop effect" occurs when powerful shower and thunderclouds can be seen around an observation site. These clouds, up to 12 km high, can be observed up to a distance of 50 km and more. The probability of seeing thunderclouds around you on a thunderstorm day is therefore very high. However, the thunderstorm cells themselves are often only very small, which can be seen well on rain radar on such days. However, this means that the probability of being hit by the thunderstorm is only relatively small. It gives the impression that the thunderstorms would pass if you weren't hit again.

In some regions, however, the "backdrop effect" cannot serve as an explanation for passing thunderstorms in certain weather situations. This means locations in the lee of a mountain range.

Even smaller mountain ranges can act as a so-called "weather divide". If there is a corresponding flow, the thunderstorms tend to split up on the mountains and then pass the observation site. You can imagine it like a river, where a stone protruding from the water deflects the water masses. Behind the stone the current is only weak, while away from it the water is carried away. However, if there is a different flow to the mountains during a thunderstorm, so that the location is not in the lee of the mountains, the location can still be hit by a thunderstorm.

Dipl.-Met. Simon Trippler
German Weather Service
Prediction and advice center
Offenbach, June 16, 2011

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