Europe, especially the South, is affected by an intense heat wave. The south-east of France is also affected by what meteorologists call a “heat dome”. What does that mean ?
The heat wave currently affecting the northern hemisphere will intensify further on Tuesday July 18. In Italy, temperatures exceed 40°C, and we even expect 48°C in Sardinia. In Spain, the seasonal norms are exceeded by almost 15°C, and Greece is affected by fires which have forced 1,200 children to evacuate their summer camps. In France too, very hot weather is expected, with peaks above 40°C in places. Seven departments have also been placed on heat wave orange vigilance by Météo France.
>> MAP. Heat wave: what are the previous heat records near you?
To explain this stifling heat, meteorologists speak of a heat dome. What is it about ? How much longer will the mercury in the south of the country panic? We take stock.
What is a heat dome?
We talk about a dome, but we could also talk about a bell, or quite simply a saucepan. Imagine that on the ground, the bottom of our saucepan, it is hot. Where does this heat naturally escape? By the top. It is the same with the heat on the ground which is evacuated in the airs. Now, imagine now that we put a lid on our saucepan, it’s our dome. The heat is trapped, can’t escape, so on Earth, we simmer, and the temperature gets hotter and hotter.
In fact, to explain it a little more complexly, our cover is a high pressure zone, an anticyclone that stagnates, blocks rain, wind and the rise of hot air. There is therefore no more air circulation. Down below, the air remains warm and even warms up.
When and how will this dome disappear?
It is currently over Italy, and the edge of the “lid” is over southeastern France. This is why Météo France has placed seven departments on heatwave orange vigilance: Vaucluse, Var, Corse-du-Sud, Haute-Corse, Alpes de Haute-Provence, Alpes-Maritimes and Pyrénées- Oriental. A priori, according to Météo France, the heat peak will take place on July 18 and 19. This dome will disappear when the anticyclone finally moves.
Are heat domes due to global warming?
A meteorologist from Météo France joined by franceinfo assures that no, that there have always been heat domes. Where climate change comes into play, on the other hand, is that it makes them stronger, more intense. This is particularly the case in recent years in the northern hemisphere, where heat waves follow one another. As during the summer of 2022 in France, where June, July and August had only been a succession of heat waves and fires, from the Gironde to Finistère, from which we are still recovering with difficulty a year later.