Massimiliano Fazzini, professor of climate risk at the University of Camerino: The strongest thunderstorms are unleashed on the eastern part of the Alpine chain
While the Centrosud still under the effect of the heat, the Alpine belt hit by heavy storms: today yellow alert from Lombardy to Friuli-Venezia Giulia. What caused this division?
To the enormous temperature contrast between tropical air masses from the south and oceanic ones from the west, says Massimiliano Fazzini, professor of climate risk at the University of Camerino and head of the Sigea working group on climate change. The Alps are the demarcation area. A strong instability forms: the hot air rises rapidly in altitude, creating clouds full of humidity that bring heavy rains, thunderstorms and gusts of wind.
There were similar effects to Storm Vaia on Tuesday. Arpa Veneto reports a gust at 188 km/h on the Pale di San Martino and winds with hurricane power. How are such intense phenomena formed?
These are violent descending currents called downburst. They fall from the top of cumulonimbus clouds from 13 km high and at the base they have speeds comparable to tornadoes. Tuesday's episode was born in different contexts than Vaia, even if the results were similar. Vaia was a depression fed by a large warming sea colliding with cold air from Northern Europe. On Tuesday there was an extreme phenomenon of the contrast between very hot Saharan air and cooler air from the North Atlantic.
The Moena flood of 2018, last year the collapse of the Marmolada glacier and mudslides in Val di Fassa. What happens in the Dolomites?
To the east the Alps have lower altitudes: it is easier for the Atlantic air to cross the watershed and collide with the warm subtropical air. In the eastern Alps, thunderstorms are stronger and the maximum intensity occurs in Carnia and in Friuli. However, all climatologists agree that the Alps are among the areas in the world most affected by climate change.
July 19, 2023 (change July 19, 2023 | 22:12)
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