A clear line separates the mountains, as if they were in two different seasons: autumn-toned meadows and forests on one side, and a blanket of winter snow on the other. However, what makes the photos arriving from the Cuneo area incredible in recent days is the order of the additions: the snow is in fact relegated to low altitude, while the mountain tops, usually cold, show the typical landscape of milder temperatures. As meteorologist Andrea Vuolo explains on the “Weather in Piedmont” page, it is a perfect representation of a phenomenon known as thermal inversion, which last weekend in the province of Cuneo caused freezing temperatures in the valley bottoms and autumn heat above 1,600 meters.
The mountains of Prato Nevoso and Artesina were affected, especially on January 5th. And as Vuolo clarifies, it was a dynamic characterized by cold and heavy air, full of water vapour, which remained in the lower layers of the atmosphere, with fog and low clouds rising from the Cuneo plain which caused sleet and frost on the vegetation.
At the same time, an influx of mild air, of sub-tropical origin, positioned itself above the frozen layer, causing a temperature range of 12-15 degrees over just a few hundred metres. In this way, between 1,600 and 3,000 meters the temperature remained steadily above zero for several hours, while further down frost and sleet covered the landscape with a white blanket.