This explains the biggest storm of the century in Spain, which caused dozens of deaths

This explains the biggest storm of the century in Spain, which caused dozens of deaths


Over 95 people have died and dozens are still missing due to the severe floods that hit mainly the Valencia region in eastern Spain.




More than 90 people have died and dozens are missing due to the severe floods that have mainly affected the Valencia region in eastern Spain.

Within hours, the equivalent of a year’s rain fell in some areas, causing massive floods that devastated entire cities and left thousands of people stranded.

Some locations recorded up to 445.4 liters of rainfall per square meter.

The rains, which arrived accompanied by strong winds and tornadoes, were caused by a meteorological phenomenon known locally as High Level Isolated Depression (Dana, in its Spanish acronym), which affected a vast area of ​​the south and east of the country.

A common phenomenon in the Mediterranean

The term Dana began to be used by Spanish meteorologists a few decades ago to differentiate the phenomenon from the so-called “cold drop”, a more generic expression that is usually used to refer to any situation of intense and abundant rain, especially on the Mediterranean coast of the Iberian peninsula during autumn.

Dana is a phenomenon in which a mass of very cold polar air isolates itself and begins to circulate at very high altitudes (between 5,000 and 9,000 meters), far from the influence of atmospheric circulation.

Then, when it collides with the warmer, more humid air that is normally present in the Mediterranean Sea, it generates strong thunderstorms, especially in late summer and early autumn, when sea temperatures are higher.

“This creates an extremely unstable environment, and that’s when the air rises. This quickly allows the storm clouds to actually fly, with the help and encouragement of winds that reach higher areas and rise as well And the higher the storm clouds, the more humidity there will be,” explains BBC meteorologist Matt Taylor.



The Spanish Meteorological Agency described the current storm as

This phenomenon can last several days and is accompanied by a drop in temperatures, a very unstable atmosphere and extreme weather phenomena, as we are currently seeing on the east coast of Spain.

Unlike a common storm, which moves eastward, Dana could stay in the same place for several days or even move westward, according to the Spanish Meteorological Agency (Aemet, from its Spanish acronym).

Not all Danas, however, generate extreme weather conditions like this.

Their destructive potential emerges precisely when they mix with the warm temperatures of the land and ocean.

“Danas are a relatively frequent structure in our latitudes (Spain) and, fortunately, most of them do not make the news,” explains meteorologist Delia Gutiérrez, from Aemet, on the agency’s blog.

Historically, Spain has recorded Danas remembered for their destructive consequences, such as that of 1973, which affected Almeria, Granada and Murcia, in the south-east of the country, causing numerous deaths and material losses.

Aemet has classified the current storm as “the most adverse of the century in the Valencian Community”.

“It was a historic storm, on par with major Mediterranean storms, and among the three most intense storms to hit the region in the past century,” the agency added.



Scene of the destruction caused by the Dana phenomenon in the Valencia region

Climate change

According to experts, the increasing frequency of Danas and the increasing intensity of precipitation are closely linked to climate change.

“Without a doubt, these explosive rains have been intensified by climate change,” says Friederike Otto, of the University of Imperial College London, UK, who leads an international team of scientists trying to understand the role that global warming plays into this phenomenon. type of event.

“With every fraction of a degree of warming caused by fossil fuels, the atmosphere can hold more moisture, which leads to heavier rainfall.”

The progressive increase in temperature of the Mediterranean Sea facilitates the creation of conditions for the energy and humidity necessary for the development of a more powerful Dana.

Warm, moist air on the sea surface rises rapidly, giving rise to high, imposing clouds that are carried towards the coast, causing large amounts of rain.

Researchers say climate change directly impacts the amount of rain carried by these clouds, with an increase of 7% for every degree C of warming.

“We are seeing an increase in these phenomena as our climate warms,” explains BBC meteorologist Matt Taylor.

“Although such events have happened in the past, they are becoming increasingly common.”

Last year, a study by the American Meteorological Society found that there has been an increase in Danas on a global scale since the 1960s.

Furthermore, when rain begins to fall, it falls with greater intensity on soils that are no longer able to absorb high levels of water.

“In addition to increased extreme rainfall, we are seeing a hotter summer, which can ‘cook’ the soil and reduce its water absorption capacity,” explains Mark Smith, a professor at the University of Leeds, in the United Kingdom. United.

“In turn, this amplifies the more direct effects of increased rainfall intensity, as more water reaches rivers.”

There is also debate among scientists about whether a warmer world would slow these storms, which would exacerbate the amount of rain they produce.



The Dana phenomenon caused a series of material damage in eastern Spain

In September, Storm Boris caused death and destruction in several Central European countries, once again reinforced by high temperatures in the Mediterranean.

Scientists say this slow-paced disaster has become twice as likely due to climate change.

In Spain, the lack of accurate warnings has led to criticism that more could have been done to prevent the tragedy. But meteorologists say predicting the path of fast-moving, intense storms is a very complicated task.

One problem highlighted by the floods in Spain is the inability of modern infrastructure to cope with extreme flood events.

As some researchers have pointed out, our roads, bridges, and roads were built to cope with last century’s climate, not today’s.

Source: Terra

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