Take shelter under a tree, wear plastic soles or not answer the phone… We checked five misconceptions about thunderstorms

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There are good practices… and myths under the storms. Waterspouts, strong winds, hail and a sky streaked with lightning: thirteen departments of the Mediterranean arc and three departments of Normandy were placed on alert by Météo France in the face of a “risk of violent phenomena” Wednesday August 17, 2022 .

Forecasters thus expect “locally violent thunderstorms with strong rainfall intensities, locally reaching 80 mm in a short time, with hail, and strong gusts of wind of around 80 to 100 km/h“. The opportunity to take stock of what to do (and not to do) during a storm.

>> Storms in France: follow the evolution of the situation live

“30 cm of water is enough to carry a car”

Caution: flash floods could occur locally. Thus, floods were observed on the A8, the A52 and in the city of Marseille. The Old Port was flooded on Wednesday morning and the Joliette tunnel remains closed until further notice. “In three hours, a sheet of water of 37 mm in Beausset and 43 mm in Hyères was raised, with a gust of wind of 116 km / h in this town“, indicates for its part the prefecture of Var.

And the prefecture, like Road Prevention, to recall that “30 cm of water is enough to carry a car. The association specifies that “dn the case where the water level seems high to you, do not hesitate to turn around and choose another route,ur not to cause serious damage to the engine (which does not like water) and to avoid being trapped in a completely submerged road”on its website.

The headrest rod to break the windows of a flooded car

Faced with these conditions, the authorities, and in particular the firefighters, are calling for “common sense“, like not going down into cellars and basements where the water could quickly rise. On franceinfo, Lieutenant-Colonel Ostiante-Decanis, responsible for the SDIS 13, delivers thus to the inhabitants struck by the bad weather some advice: “Do not take your car during these times, postpone your trips, stay away from waterways, do not park on banks or bridges, do not drive or walk on flooded pathseven partially. In short, avoid all situations that could put you in danger.“

Finally, recalls Road Prevention: “If the situation deteriorates, there is no point in trying hard to protect your vehicle. Better to worry about its occupants, driver and passengers.“But what to do when a vehicle is then swept away by water and finds itself partly flooded? According to the firefighters, the first thing to do is not to open the doors: they are blocked with the water pressure. It is therefore urgent to open the windows, manually or electrically (the electrical part of a car is supposed to be waterproof), and to switch on the hazard warning lights, in order to be spotted more quickly by rescue.

Finally, if the windows do not open, there is one last solution: grab hold of one of the vehicle’s head restraints, pull it out of the seat and hit a corner of the window with one of the stems of these latest, as shown in this video from the Jamy’s Worldfor example.

Avoid trees, don’t run and “roll into a ball”

In addition to the rapid rise of water, lightning is at the heart of several myths or practices to avoid. While several million lightning strikes France each year, there are 200 people struck down each year. According to the emergency services, 10% of these victims die of their injuries, while 70% of the survivors retain serious sequelae.

Thus, during a thunderstorm, a few simple tips remain to be applied. And the first is simple: take shelter, regardless of geographical location. In town, it is therefore recommended to take shelter quickly in a building or a house and to close the doors and windows. The car remains a shelter of choice: the passenger compartment (closed and non-convertible) plays the role of “Faraday’s cage”, which protects the passengers unharmed if the vehicle is struck by lightning.

Outside, the situation is more delicate: it is first recommended not to run, as this is more likely to attract lightning via the “step voltage” phenomenon. You should also stay away from nearby trees or electricity pylons – or even take shelter under an umbrella. The Protection Foudre association thus recalls that it is worth better lie down on the ground and get into a ball, and this at a distance of several meters between each person, who must absolutely not touch each other, the human body being a conductor. The ideal is to wait until the situation calms down on an insulating material, such as a backpack, a plastic bag or even a sleeping bag: lightning can, in fact, travel through the ground.

In the mountains, you have to move away from the summit and find as much refuge as possible in order to shelter yourself squatting, far from metallic objects, without touching the rock faces. Finally, at sea, it is recommended to get out of the water immediately if swimming, and to reach the shore as quickly as possible, before lying down on the sand, without an umbrella. Water is indeed an excellent electrical conductor.

Wearing rubber boots prevents being struck down

This is a “advice” that we sometimes hear. However, it is still dangerous to stay under lightning, outside, even with rubber boots or any other plastic sole. Lightning scattering in the ground, a difference of feet of 1 meter causes a voltage of 5,000 volts. Although it is a material that does not conduct electricity well, the fact remains that rubber offers little protection against lightning.

>> Weather: Cévennes or Mediterranean episodes, “medicane” or “V” storms… We explain these phenomena to you

Do not answer the phone (and do not take a shower)

The scene marked the readers of Tintin: in the album The Seven Crystal Balls, Hergé imagined a ball of fire coming out of a telephone handset on a stormy evening. In reality, it is a very real, but rare phenomenon: ball lightning.

It remains that, during a storm, the risk of lightning does exist inside a shelter, such as a house. It is therefore recommended to close all doors and windows and unplug electrical appliances. A precautionary measure that aims to prevent lightning from spreading through the electrical network and causing damage – or even the explosion – of television, a computer or a landline telephone. On the other hand, the cell phone does not involve any particular risk. Finally, and we know little about it: you must avoid taking shelter in your bathroom during a storm. Metal piping is likely to conduct electricity in the event of lightning.

It should be noted, finally, that the authorities point out that a “safety kit” is easily achievable in the event of violent storms.

The Var prefecture thus recommends equipping yourself with a radio and flashlights with spare batteries, non-perishable food and drinking water, warm clothes, or even a copy of identity papers To hold “at least three days“.


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