What is a Mer du Nuages?
If you’ve spent any time skiing or snowboarding in the French Alpine resorts (or even in other ski resorts including Scotland), you’ll have likely come across the somewhat peculiar phenomenon known locally as a Mer du Nuages (or, literally, Sea of Clouds). But just what is a Mer du Nuages and how does it form? Read on for a brief guide.
What is a mer du nuages?
In a mer du nuages, it can typically be raining (or even snowing) in the valleys while on the mountain summits you’ll be bathed in sunshine. The picture above was taken at the summit of Roche de Mio above Plagne Bellecôte and Belle Plagne, clearly showing the Bellecôte glacier pistes bathed in sunshine while the sea of clouds laps up against the lower slopes.
What causes a mer du nuages?
A mer du nuages needs a couple of factors to occur including anticyclonic conditions where there is little wind and a temperature inversion which allows clouds to form lower in the coolness of the valleys while up high the warmth persists. The above photo shows the phenomenon in the Champagny sector of La Plagne, extending all the way over to the peaks of Trois Vallées.
If there is sufficient moisture in the air of the valleys (yet enough warmth), this wet air will slowly rise to form a lower layer of clouds in between the valley floor and the summits – hence the reason it can often be miserable down low yet warmer up high.
In the winter, the sun typically isn’t warm enough to sufficiently burn off this moisture so a mer du nuages can continue to build. Indeed, if the high pressure persists and there’s a lack of wind, the mer du nuages can sometimes last many days until it eventually breaks down.
The deceptive nature of mer du nuages
So, the moral of the tale? Next time you pull the curtains in your La Plagne accommodation to see a drizzly, cold or overcast day don’t just throw in the towel. There’s every chance the conditions could be great up high so take a quick look at the La Plagne webcams at altitude and check the La Plagne weather forecast before calling it a day. The picture above shows the boundary level of a sea of clouds just above Plagne Centre, Plagne Villages and Plagne Soleil near the Colosses detachable chairlift.
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