Low sea level

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 are going to tell you all the characteristics, damages and frequency with which rissagas take place.

What are rissagas

Sea level reduction

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 steep descent, the entire port is almost empty in a matter of minutes. As a result, the fishermen's boats touch the bottom and many of the fish die from suffocation. However, other areas of the port are not completely empty but you can see a large drop in the water level. This causes many boats to be stranded for a time.

Minutes later, the water suddenly returns to the port again and this causes all the boats to crawl and be hit against each other. In addition, many of the boats sink and cause extensive damage in general. On some occasions we find a sudden avalanche of water that causes some flooding in the 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

Rissagas in Ciudatella

As expected, this phenomenon is quite strange and attempts are made to find the reason for its origin. This phenomenon has been known for quite some time, especially from the Ciutadella. There are some references that speak of the sinking of ships in the port of Ciutadella in the XNUMXth century. And is that all these tides have an extraordinary amplitude and occurs in just a short period of time.

Normally, it is taken into account that the amplitude of the astronomical tides of the Mediterranean usually have about 20 centimeters in a period of several hours. This is something that is barely visible to the naked eye. However, rissagas originate amplitudes of more than 2 meters in length in just a period of 10 minutes.

The origin of rissagas has not been well known until recent times when there is more knowledge of meteorology and the operation of the tides. It was thought that the origin of rissagas could be astronomical. This means that it has a type of operation similar to that of the tides. It was also thought that it could have a seismic origin. It could happen because of underwater earthquakes that generate various waves that would be amplified to reach the port. However, All these hypotheses were strong enough to be able to explain the phenomenon in particular. The least that could be explained was the abundant frequency of this phenomenon in this particular garden 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 sea. Some authors think of the theory that rissaga is produced by an influence of gravitational waves that are generated in the middle levels of the troposphere. These gravitational waves take place because of the wind shear caused by oscillations in atmospheric pressure more at 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 must blow in front of a deep trough that affects the Iberian Peninsula.
  • For levels below 1500 meters There must be a quality air mass that causes the existence of a strong temperature inversion between this level and the air above the sea surface. The air on the surface of the sea will be colder than this.
  • there must be a weak or moderate east component wind flow on the surface.

This last condition if you have recently verified that it is not completely necessary for the rissagas to take place. At some time, rissagas have been observed with winds from the south or southwest on the surface. Mediterranean meteorology experts have come to the conclusion that these favorable atmospheric conditions for rissagas occur during the warm half of the year. Therefore, the highest frequency of this phenomenon occurs between April and October.

Time associated with the rissagas

One of the fundamental aspects that to take into account for the prediction of the monitoring of the rissagas is the atmospheric weather that characterizes these situations. In the days in those that produce the rissagas the sky is usually covered by layers of dense and opaque altars. Normally it is rare that there is cloudiness below, but it is characteristic of the sky that is cloudy and yellowish due to the haze. The haze seems from the dust that creeps from this African continent.

At other times there are only a few scattered clouds that do not denote significant vertical movements either.

I hope that with this information you can learn more about the phenomenon of rissagas.

Leave a Comment

Your email address will not be published. Required fields are marked with *



  1. Responsible for the data: Miguel Ángel Gatón
  2. Purpose of the data: Control SPAM, comment management.
  3. Legitimation: Your consent
  4. Communication of the data: The data will not be communicated to third parties except by legal obligation.
  5. Data storage: Database hosted by Occentus Networks (EU)
  6. Rights: At any time you can limit, recover and delete your information.