What is a waterspout or “waterspout” and what happens if it touches land?
A marine sleeve is a powerful whirlwind of wind that develops over a large surface of water, be it the sea or a lake. Generally, It is the name given to a tornado that moves on water and, therefore, they share almost all the characteristics of their terrestrial counterparts. In fact, they can go ashore and transform into tornadoes or vice versa. Waterspouts generally consist of a funnel cloud that emerges from the base of a cumulonimbus and reaches the surface of the water, where it is lifted and pulverized by strong winds, forming a cloud of water droplets that rotates at high speed.
Like it happens in tornadoes, the circulation of winds in a marine sleeve responds to a balance between the centrifugal force of its circulation and the low pressure inside it, which tends to make the air fall towards the center. As the air approaches the axis of rotation of the vortex, it accelerates its speed due to the conservation of angular momentum. This is easily visible with the example of a skater turning on himself with his arms extended, if he contracts them quickly, he will be transferring part of his mass to a point closer to the axis of rotation and his turning speed will increase, spinning. much faster.
Waterspouts are classified into several types just like tornadoes, being common to distinguish between non-supercellular and supercellular or mesocyclonic. The first type is the most common and is usually associated with conventional storms such as non-mesocyclonic tornadoes (landspouts), however, there is a single important difference with respect to terrestrial tornadoes: the surface of the ocean has no obstacles and its temperature Constant surface area facilitates convection and the stability of the circulation of these eddies.
They are, therefore, relatively more frequent than their counterparts on land, non-mesocyclonic tornadoes, especially the weaker specimens. They can also be associated with clouds and small convective currents that could hardly generate a tornado on the ground, so it is not strange to see marine sleeves dangling from medium-sized cumulus clouds and generate small vortices, with winds of just over 70 km / h. These are often called “non-tornadic” sea sleeves that dissipate rapidly when interacting with land. They should not be underestimated for this reason, since cases associated with strong storms can reach higher speeds, between 180 and 250 km / h and cause serious damage if they penetrate the mainland.
The second, less frequent type is that of supercellular waterspouts. They share all the characteristics of supercellular tornadoes and pose a much greater threat to both boats and the shoreline, if they ever reach it. Like most supercellular tornadoes, They tend to be relatively longer and longer, and the wind speed can be well above 200 km / h in intense cases..
Marine sleeves in Spain
The truth is that it is a common phenomenon in coastal areas of temperate seas during episodes of storms and thus in the Iberian Peninsula, although its small size and short movement prevents in many cases that they are a direct threat on land. The coasts of the Mediterranean are a breeding ground for this type of phenomenon, especially in autumn, when the sea is at a higher temperature and the first autumn fronts and storms begin to affect the Mediterranean basin, triggering convection. They also appear relatively frequently on the Atlantic and Cantabrian coasts.
A recent particular case was the one that occurred on April 15, 2020 in Cádiz: a marine sleeve touched earth damaging several boats and affecting the facilities of the observatory of the State Meteorological Agency, demolishing the meteorological checkpoint of the station. The anemometer registered a gust of 140 km / h.
UNone of the most shocking and intense cases took place on the morning of August 29, 2020 in Banyalbufar (Mallorca). It was tried of a supercellular marine sleeve that made landfall and entered the island, felling thousands of trees and causing significant material damage on some farms, comparable to an EF-2 intensity on the improved Fujita scale, attributed to wind speeds comprised between 179 km / h and 218 km / h.