The phenomenon known by the name of laughing It is an event that occurs in some coves and ports in the Balearic Islands. It could be translated into Spanish as hangover. It is a rather curious phenomenon that consists of various oscillations in sea level that can reach up to 2 meters in width in periods of only 10 minutes. It is not an exclusive phenomenon of this island, but it is true that it happens quite frequently.
In this article, we'll tell you all about the characteristics, damage, and frequency of the rissagas phenomenon in the Balearic Islands.
What are rissagas
This name is due to a phenomenon that occurs with great frequency in the Balearic Islands. Although it is not unique to this site, it does take place in the port of Ciutadella in the town of the island of Menorca. When this phenomenon occurs, it manifests itself as a sudden drop in the water level in the port. With this sharp drop, the entire port becomes almost empty in a matter of minutes. As a result, the fishing boats touch the bottom and many of the fish die from suffocation. However, other areas of the port are not completely empty, but a significant drop in the water level can be observed. This causes many boats to remain stranded for a while.
Minutes later, the water suddenly returns to the port again, causing all the boats to be dragged and battered against each other. In addition, many of the boats sink, generally causing extensive damage. Occasionally, we experience a sudden avalanche of water that causes flooding in areas near the port. In these avalanches, we find great effect on vehicles and premises that are close to the port. Normally this phenomenon is repeated cyclically for hours. Sometimes rissagas have been found several times in the same day.
Causes of rissagas
As expected, this phenomenon is quite rare, and attempts are being made to find the reason for its origin. This phenomenon has been known for quite some time, especially in Ciutadella. There are some references that speak of ships sinking in the port of Ciutadella in the 20th century. All these tides have an extraordinary amplitude and occur in just a short period of time. Normally, it is assumed that the amplitude of Mediterranean astronomical tides is usually about XNUMX centimeters over a period of several hours. This is something that is barely noticeable to the naked eye. However, The ripples generate amplitudes of more than 2 meters in length in just a period of 10 minutes.
The origin of rissagas has not been well understood until recent times, when more was learned about meteorology and the functioning of the tides. It was thought that the origin of rissagas could be astronomical. This means that they function in a similar way to the tides. It was also thought that they could have a seismic origin. They could occur due to underwater earthquakes that generate various waves that would be amplified upon reaching the port. However, All these hypotheses were not sufficiently conclusive to explain the specific phenomenon. What was least understandable was the high frequency of this phenomenon in this particular port and not in others.
The true cause was known in 1934, after various studies on extraordinary fluctuations in sea level. Studies suggest that the cause of rissagas is atmospheric. Large sudden swings in sea level are associated with other sudden swings in atmospheric pressure. In the case of Ciutadella in the Balearic Islands are produced as a result of the interaction between the atmosphere and the seaSome authors suggest that rissaga is caused by the influence of gravitational waves generated in the middle levels of the troposphere. These gravitational waves are caused by wind shear caused by fluctuations in atmospheric pressure at the surface level.
Weather conditions
There are various atmospheric conditions that are more characteristic to promote rissagas. The 3 main atmospheric conditions that favor the appearance of this phenomenon are the following:
- There should be strong southwesterly winds in the middle and upper levels of the troposphere. These winds should blow ahead of a deep trough that could affect the Iberian Peninsula.
- For levels below 1500 meters There must be a quality air mass that causes a strong temperature inversion between this level and the air above the sea surface. The air at the sea surface will be colder than this.
- there must be a weak or moderate east component wind flow on the surface.
This last condition has recently been shown not to be completely necessary for rissagas to occur. Rissagas have occasionally been observed with southerly or southwesterly winds on the surface. Mediterranean meteorology experts have concluded that these favorable atmospheric conditions for rissagas occur during the warmer half of the year. Therefore, this phenomenon is most common between April and October.
Time associated with the rissagas
One of the fundamental aspects to take into account when predicting and monitoring floods is the weather that characterizes these situations. On days when When rissagas occur, the sky usually remains covered by layers of dense and opaque altostratus. Normally, cloudiness is rare below, but the sky is characterized by a cloudy, yellowish hue due to haze. The haze appears from dust drifting from the African continent.
At other times there are only a few scattered clouds that do not denote significant vertical movements either.