This June it has repeatedly rained “sand” and the days were characterized by a cerulean sky with orange hue. It is the fault of the Sahara’s sands, more properly we must speak of dust, since the grains of sand are too heavy to be carried in suspension in the air.

Every year tens of millions of tons of mineral dust are lifted into the atmosphere from the desert and with certain wind circulations at high altitudes are also transported to Europe. On the territories adjacent to the African coasts, such as Spain, Sicily, events are necessarily more frequent but in some cases desert dust can also overcome the barrier of the Alps, reaching the heart of Europe and even beyond, sand was even found in the snow of Scandinavia.

It is not an unusual phenomenon but in the last decade the frequency, the duration and the intensity of the episodes is increased and the researchers point the finger on the climate change, seen the strong drought in course on West Africa and the succession of the numerous blocking configurations of the synoptic circulation on the Mediterranean.

The most favorable conditions to the phenomenon on our seas are when a low pressure between the Atlantic, the Iberian Peninsula and France is deepening in contrast to the presence of a high pressure area between the Italian Peninsula and the Balkans. Scirocco and Libeccio winds lift the dust from North Africa up to 10 thousand meters, where it can be transported north for thousands of kilometers without obstacles.

Nowadays, thanks to the use of satellites, it is possible to control the displacement and the extension of the sand mass, while weather models are able to predict the phenomenon in detail.

Credits ADAM Platform Copernicus

Alessandro Casarino – Navimeteo