While the orange alert is active for the risk of strong thunderstorms, it is difficult not to notice in these days in Milan and Lombardy an orange sky and “dust” sediments on windows and cars.
This is not an unusual phenomenon. It’s Saharan sand. The clouds that are covering Northern Italy come from the contrast between a cyclone off the coast of the British Isles and the African anticyclonic promontory on the Mediterranean basin, which attracts currents from the North African desert.
Because the sand arrives in Italy
The arrival of dust from the Sahara desert is a function of the general atmospheric circulation, underlines Francesco Nucera on 3bMeteo.com. Every year over 60 million tons of nutrient-rich mineral dust is kicked into the atmosphere. The synoptic conditions for its arrival from the Sahara over the Mediterranean are a low pressure positioned just south of Iceland and a subtropical high pressure field over the central-eastern Mediterranean. Sand from the desert, in the case of strong winds at high altitude, is also found in the heart of the European continent.
These events are normal during the spring months and extend to the UK or even Scandinavia. But we have also seen how they also happen in winter which should normally be the season with the lowest transport activity. These dust clouds became a regular occurrence during the winters between 2020 and 2022. A few cases also showed durations never before recorded. In 2022, for example, Spain recorded levels of dust in the air five times higher than the recommended air quality threshold. All in all, 2023 was a quiet year while in 2024 activity seems to have increased again. Several factors could contribute to these recent intense events. One of these is the ongoing drought in Northwest Africa, the other is the traffic-blocking conditions. These circulatory conditions can then exhibit a wide variety of configurations. Scarcity of rainfall is one of the causes that affects desertification. Severe or very serious areas are found in the five Mediterranean countries of Africa: Egypt, Algeria, Libya, Morocco and Tunisia.
