DANA: the climatic phenomenon which paralyzed part of Spain | The most affected region was Catalonia

Spain has been shaken in recent hours by a particular climatic phenomenon: a DANA, an Isolated High Level Depression. The phenomenon caused flooding in various regions of the country.

DANA occurs when an isolated atmospheric depression occurs at high levels as a result of the collision of a cold high air mass with warm surface air, resulting in heavy rains and storms.

In the case of Spain, the floods caused extensive material damage in Catalonia, where a motorway had to be closed due to the flooding. It has also been felt in the Valencian Community and the alert continues in cities like Madrid, Zaragoza, Cuenca, Guadalajara, Teruel and Pamplona.

Strictly speaking, DANA can be defined as “a low pressure system that manifests itself especially in the middle and upper layers of the troposphere”, according to the State Meteorological Agency of Spain (Aemet).

“To understand its formation, you have to look at the polar jet. It is a very intense wind current at high levels of the troposphere that flows from west to east and separates the cold polar air (located north of this current) from the warm tropical air (south of the current) “.

“The polar jet ripples, like the meanders of a river, and the ripple is sometimes so intense that the wave itself is strangled and detached from the polar jet: at this point there is a kind of large pocket of water. ‘cold air surrounded by warmer air and we have already formed the DANA,’ added Aemet.

What is striking is that this phenomenon has developed globally over the past half century, according to records from the American Meteorological Society.

Areas such as southern Europe, the US east coast, northeast Pacific, and northwestern North America may be prone to its consequences, as may South Asia, the Australia, New Zealand and South America.