First the good news: while 300 people were struck by lightning in Germany in the 19th century, today the figure is "only" three to seven per year. The reason: whereas in the past people often stood defenceless in vast fields, today they can reach shelters such as cars or houses much more quickly. And now the bad news: anyone travelling in high alpine terrain during a thunderstorm today has practically the same conditions as people in the 19th century. The next shelter in the mountains may not be waiting until after the next mountain pass and the car is in the valley anyway. What's more, thunderstorms develop much faster in the mountains due to the slopes and you often don't see them approaching behind the next mountain. Suddenly, the black towers of clouds already rise above the rocky ridges and the storm strikes in a flash.
Thunderstorms are still one of the greatest dangers in the mountains today. In Switzerland alone, 900 thunderstorms rained down in 2006. And anyone who has ever been caught in such a storm in the middle of a lonely rocky landscape knows how dramatically thunder and lightning can rage in the mountains. It is not uncommon for the air to crackle - the clouds are so charged. Lightning flashes every second and the thunderclaps reverberate off the rocks. Small streams can quickly become torrents due to the onset of rain and hail, and there is a risk of landslides and falling rocks on steep slopes. Anyone who behaves incorrectly now risks their life. This is the best way to protect yourself:
1. get up early
Unfortunately, the best months for touring the Alps coincide with the peak thunderstorm season. From May to August, you can expect heat thunderstorms in the mountains almost every day. They occur locally and are therefore difficult to predict. Nevertheless, they are reasonably predictable, as they usually only strike in the afternoon. So start your tour as early as possible so that you are back by 4 p.m. or have already reached the next stage destination during a crossing of the Alps.
2. study the weather forecast
If you want to tour through the Alps, you should study the weather map at least the evening before. If a cold front with thunderstorms is forecast, plan your tour accordingly or postpone it. Travellers crossing the Alps should always ask the hut warden or hotelier for the latest weather forecast and possibly change the route to a safer route near the valley.
WHEN THE STORM IS ALREADY APPROACHING
3. seek shelter
First thing to do when you see a thunderstorm approaching in the mountains: Look on the map for the nearest shelter.
- CALCULATE Calculate the approximate distance of the thunderstorm as follows: Count the seconds between lightning and thunder, divide the result by three and you will get the approximate distance of the thunderstorm in kilometres. (Speed of light: 300,000 km/s, speed of sound 330 m/s) Then decide which escape measures you have enough time for. If the time between lightning and thunder is less than ten seconds, the thunderstorm is already dangerously close. You should no longer take the risk of quickly cranking over the next pass. The aim now is to avoid the highest point in the terrain and thus a potential lightning strike location. The correct and faster direction in the event of an impending thunderstorm is therefore always downhill. Suitable shelter options:
- HUTS: if possible with a lightning conductor (a kind of antenna that diverts the lightning on the outside of the hut to the ground)
- HOLES: Go in as far as possible, but keep a good distance from any wet rock faces (lightning conductor)
- DENSE FOREST: Never stop at the edge of the forest. Walk about 50-100 metres into the forest, but keep your distance from the individual trees in case they are hit!
- MULDE: If there is absolutely nothing nearby to protect you, at least find a hollow in the terrain. Place your bike and all metal objects at least 50 metres away, switch off all electronic devices (GPS, mobile phone) and crouch down (over your rucksack) in the hollow. Keep your legs close together and do not rest your arms on the ground, but keep them close to your body. This will minimise the tension in your stride.
YOU SHOULD DEFINITELY AVOID THESE PLACES AND SITUATIONS DURING THUNDERSTORMS:
- SINGLE TREES with overhanging branches
- WATER RUNS
- ROCKY RIDGES, PEAKS
- METAL OBJECTS (summit cross, iron ropes in gorges, metal fences)
- STEEP SLOPES, due to landslide and rockfall hazard
- IN THE GROUP stand close together - keep a distance of at least three metres between them!
THE TWO MOST COMMON TYPES OF THUNDERSTORM
Heat storm
They can occur daily in the summer months, occur locally and are difficult to predict. But they usually only strike in the afternoon from 3 pm. Especially in regions with a high proportion of rock, because this is where the sunlight is most intense. The warm, humid air rises and cools down in the process. This causes the first clouds to form by midday. If they form a kind of anvil (cumulonimbus), a thunderstorm is not far away. Nevertheless, warm thunderstorms usually dissipate quickly and then the sun shines again.
COLD FRONT THUNDERSTORM
When cold air masses push under the warm air on the ground, clouds also pile up quickly. This often forms a thunderstorm front several kilometres long, which brings with it a drop in temperature and persistently bad weather. The advantage of this type of thunderstorm is that it can be seen a few days in advance and is easily recognised by the rapid drop in the barometer.
Gitta Beimfohr
Editor
