Bad weather in the North: thunderstorms and lightning after the heat wave

After the heat waves that have gripped Italy for weeks, a phase of instability with violent thunderstorms and intense lightning activity arrives in the north, and to a more limited extent in the centre. A phenomenon typical especially of the Alpine regions, a true "hot spot" of lightning generated by the contrast of masses of hot and cold air.

"When we have a hot period and then cooler air arrives to interrupt this phase, the contrast between a colder air mass at altitude and warmer air in the lower layers makes the atmosphere unstable", Lorenzo Giovannini, an atmospheric physicist at the University of Trento, told ANSA.

This clash between different air masses triggers "more violent vertical motions and therefore the formation of intense thunderstorms", which bring with them not only lightning, but also hailstorms and strong gusts of wind. A phenomenon typical especially of mountainous areas where it is normal to expect afternoon thunderstorms with a certain frequency "which however have so far been absent due to the great stability of the African subtropical anticyclone, thus causing drought problems", added Giovannini.

And it was precisely because of this drought that some fires were triggered in the Alpine regions: "one of these in Val di Non was caused by lightning that fell on land made vulnerable by the lack of rain", added the atmospheric physicist. As highlighted by real studies, more generally the Alpine arc is considered a real lightning hot spot on a global level, therefore a normal phenomenon and one to which we need to pay close attention. "The mountains in this period are very busy, there has been a lot of talk about 'overtourism' in the Alps or the Dolomites, it is good to remember that the mountains can be a dangerous environment if you don't have the right precautions, being surprised by a storm can have tragic consequences".