Italy, like many other Mediterranean regions, is facing increasingly hotter and drier summers. This phenomenon is closely linked to global climate change, but also to other less well-known factors, such as the influence of Indian monsoon. The complex atmospheric dynamics that develop in India during the monsoon season can have repercussions on European weather conditions, contributing to the excessive heat waves that increasingly affect our country.
The monsoon season arrives in India
There monsoon season in India it is a climatic phenomenon of great importance that occurs every year, generally starting from June and continuing until September. This period is characterized by heavy rains and storms that bring relief from high summer temperatures, affecting not only agriculture and daily life in India, but also weather patterns in other parts of the world, including Europe.
Monsoons are caused by temperature differences between land and sea. During summer, the air over the Indian continent warms much faster than that over the ocean. This temperature difference creates an area of low pressure that draws ocean moisture inland, causing heavy rainfall. These rainfalls are crucial for Indian agriculture, as many crops depend on rainwater.
The strength and duration of monsoons can vary greatly from year to year, and are influenced by global phenomena such as El Niño and La Niña. For example, a strong El Niño tends to reduce the intensity of monsoon rainfall, while La Niña can lead to heavier rainfall.
Heat waves in Italy caused by the monsoon
The heat waves that affect Italy and other Mediterranean regions are often influenced by the dynamics of the Indian monsoon. When the monsoon is particularly active, it causes changes in atmospheric circulation globally. In particular, the Indian monsoon can influence the formation of Rossby waveswhich are large atmospheric currents moving from India towards Europe.
Rossby waves can in turn alter the position and intensity of areas of high and low pressure in the Atlantic and Mediterranean, contributing to the formation of persistent anticyclones that bring warm air from Africa towards southern Europe. This mechanism explains why, during years of intense monsoon, particularly hot and dry summers occur in Italy.
Another effect of the Indian monsoon is the atmospheric subsidence, i.e. downward movements of the air that compress and further heat the surface air. This subsidence can extend as far as the Mediterranean, favoring the formation of robust anticyclones that trap warm air and prevent the formation of clouds and precipitation. As a result, temperatures can rise rapidly, leading to intense and prolonged heat waves.
In the last few years, various scientific studies highlighted the importance of monitoring Indian monsoons to better predict heat waves in Europe. Research projects such as AMMA (African Monsoon Multidisciplinary Analysis), which involves bodies such as the CNR and ENEA, are improving the understanding of the interactions between the African and Indian monsoons and the Mediterranean climate. These studies are fundamental to develop climate models more accurate and effective adaptation strategies to face future climate challenges.
