The high temperature of the Mediterranean Sea, a warning for autumn?

The high temperature of the Mediterranean Sea has been one of the themes of the summer.

And not only because of the feeling of “broth” experienced by vacationers who come to the coast. Also because it can become a factor to take into account in the intensity of precipitation that traditionally tends to occur during the fall.

What is behind a possible intensification of rainfall?

The alert about what may come after the summer started following a tweet from a well-known meteorologist. In addition to the repercussion it had on Twitter, the message was replicated by numerous media outlets, some of which were carried away by a certain apocalyptic tinge.

It is true that a high seawater temperature is necessary for heavy rainfall to occur. But it is not the only condition for its triggering.

Factors that contribute to triggering torrential rains

In order for it to rain intensely, the following factors must be present:

  • Atmospheric instability, which facilitates the vertical movement of air masses.
  • High moisture content in the lower layers of the atmosphere. As the sea surface temperature increases, the amount of water molecules that evaporate increases. In other words, they change from a liquid to a gaseous state and saturate the air masses closest to the sea surface with water vapor.
  • External force or triggering mechanism, such as isolated high level depressions or DANAs (popularly known as cold drops, although they are not exactly the same thing) or fronts associated with squalls.

When we put these three factors together in the same place and at the same time, it happens that:

  • the DANA brings cold air to the upper layers of the atmosphere, increasing instability;
  • the layers of the atmosphere near the sea, warmer and more humid, rise by a process of convection. Vertical motion continues until this rising mass is cooler than the surrounding air, and
  • instability and humidity-laden air favors the formation of clouds of great vertical development that may end up discharging in the form of intense precipitation.

In summary, in a situation of high temperature of the Mediterranean Sea like the present one, the arrival of a DANA could increase the impact of rainfall.

Could this situation degenerate into the formation of tropical cyclones in the Mediterranean, also known as medicanes, if the temperature continues to rise as a result of global warming? Yes, it could be possible. In fact, the Ianos hurricane that struck the coast of Greece in September 2020 is a clear example.

In view of the phenomena that can be triggered by the high temperature of the Mediterranean Sea, monitor

As you can see, the seas and oceans play an important role in weather and climate. They absorb solar radiation and contribute to regulating the water cycle and oceanic and atmospheric circulation.

Global warming is causing the equilibrium in which these mechanisms were developing to break down. And yes, there have always been adverse phenomena and episodes of extreme weather. But little by little we are moving from anecdotal and local facts to events that happen every few years and in a generalized way.

In view of this situation and the forecasts being made by the scientific community, at Arantec we believe that one of the best measures that can be adopted is to strengthen and expand early warning systems. As we have explained on other occasions, these solutions help to minimize the effects of heavy rains.

Precipitations such as those that could be unleashed by a Mediterranean that in some areas is 5 ºC above normal values.

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