The meteorological phenomenon that gave rise to the anomalous waves last Saturday on the entire coast of Macerata (but also on the Marches and the Adriatic) is called “descent”. In Civitanova and Porto Recanati, at the end of the afternoon, out of nowhere, the water rose and reached the first rows of umbrellas, with strong gusts. Unicam professor Carlo Bisci, geomorphologist and climatologist, professor of physical geography who has been studying the coasts of our areas for years, explains what happened. “Anomalous waves accompanied by a strong wind suddenly invaded our beaches for a few meters, reaching the first rows of umbrellas and causing panic among the bathers -explains Prof. Bisci- who perhaps feared that it was a small tsunami. In reality, it was a completely different phenomenon, since tsunamis, truly deadly, are generated by landslides, strong earthquakes or volcanic eruptions that occur in the open sea, affecting large portions of the coast and as a first effect causing a rapid and strong drop in sea level, followed by waves that can reach tens of meters in height. In our case, however, the anomalous waves were not preceded by a waterfall, they only affected a few hundred kilometers of coastline, and they had a lower height than that recorded during normal swells. The origin of this phenomenon, which advanced from Romagna to Abruzzo in a couple of hours, gradually losing intensity, is what meteorologists call a “downburst”. That is, a huge storm core located in front of the Pesaro area that very quickly dumped into the sea a large amount of rain and hail which, driven by particularly strong gusts of wind (well above 100 km/h), began to travel towards the coast and then formed shorter but higher waves as a result of interference with the seabed, which was getting shallower.” change is to reduce average return times. And not especially dangerous, linked to the very strong contrast between the extremely hot and humid air masses that come from the south and the much colder ones that come down from the north, favored by the long stay in the Mediterranean of the African anticyclone -he concludes- which, with its high temperatures, causes intense evaporation on the sea surface”.