Has the sun hidden away for good in Loire-Atlantique? The question burns on our lips in these foggy times. Cédric Deschamps, meteorologist at Weather France, explains to us the reasons for this persistent fog.
The fog remains frozen above our heads. Will we ever see the sun again?
(laugh) Probably one day… To tell the truth, the sky may be covered again this Tuesday and Wednesday. And Thursday, a good part of the day…
What is this fog that lasts, that lasts, linked to?
We are under the influence of the anticyclone which is located over central Europe. And what's more, with a light wind. In summer, such parameters generally guarantee clear skies. But in autumn and winter, it is more likely to block the very lower layers of the atmosphere. Because fog is nothing more and nothing less than a cloud that touches the ground. With a thickness of 100 to 200 m, no more. If you find yourself, for example, on the Monts d'Arrée (385 m) in Brittany, you find yourself emerging from the stratus, without fog, and can observe with the clouds pressed to the ground.
If the wind was stronger, would the fog disappear?
Yes. You can also see it during the day. The slightly stronger wind sometimes helps dissipate the fog.
At the seaside too, the fog persists. Which is pretty rare, right?
On the coast, we are on an oceanic influence. With a climate that varies during the day. Whereas in the episode we are experiencing, with three to four days of fog and which persists throughout the afternoon, it is not exceptional but indeed uncommon.
In recent days, Météo France told us that the fog was going to dissipate, and yet it persisted. How do you explain it?
Because forecasts are difficult to establish. There just needs to be a little more wind, and that can radically change the cloudiness. When you look at the satellite images, you see a completely clear sky and two kilometers further away an covered sky.
