Air currents in the atmosphere are produced by various natural causes. Wind is caused by temperature differences of uneven heating of the various areas of the Earth and the atmosphere. The masses of warmer air tends to rise, and its place is then occupied by the surrounding masses, colder air and, therefore, denser. It is properly called “wind” to the flow of air moving horizontally, reserving the term “convection current” for vertical air movement. Wind direction depends on the distribution and evolution of isobaric centers; It moves from the centers of high pressure (anticyclones) towards low pressure (depressions) and its strength is greater the greater the gradient pressure. In its motion, the wind is altered by various factors such as the relief and the Coriolis acceleration.
East. The East gales are a kind of Mediterranean storm of the Catalan and Balearic coasts. It usually occurs from December to May, unexpectedly and quickly. It goes from southwest winds with clear skies and pleasant temperatures to a cold northeast with violent gusts of up to 198 Km / hour (1960). Strong waves commence, which are very dangerous for small boats and has and caused extensive damage to the ports of these areas. For example, in February 1948 such a storm of 50 metres of breakwater, destroyed the port of Barcelona, obliterating 4000 concrete blocks of 60 tons each.
Tramontana. The Tramontana is a cold wind blowing northeast or north on the coast of the Balearic Islands and Catalonia. It can last several days with very straight winds and gusts of over 100 km / hour.
East. It is a persistent wind blowing from the east. They are very common in the Alboran Sea and the Straits. They can reach 120 km / hour, causing very uncomfortable situations for navigation.
Storms. Atlantic storms arrive and they especially hit Galicia and the Cantabrian coast. In some cases they come from the final phase of tropical cyclones beginning in the equatorial zone along the coast of Africa, up to the Caribbean and the Atlantic coasts of North America and from there turn to the Peninsula. Normally by the time they reach the middle of the Atlantic on his way to Spain, they have already lost strength and stop being called cyclones, but the rest that remains is still a strong storm. For example, with cyclones Hortensia and Klaus (1984) which blew gusts of 150km / hour.
Gales. They are sudden storms that affect the Cantabrian coast and the Bay of Biscay. It produces gusty winds of up to 180 km / hour. When this occurs, the storm passes abruptly from gentle winds to south winds from the NW, with a clear sky with thundershowers. The sea becomes rough seas in a very short time. They occur between May and October and cause shipwrecks (in 1912, for example more than 100 fishermen of Bermeo died) and severe flooding in the port cities.
Strong Winds. They are called the gusty winds that sometimes occur in the Gulf of Cadiz and the lower part of Guadalquivir. They occur when strong storms are approaching the Portuguese coast.
Tornados. Although they are very rare in Spain, they have occurred, such as December 27, 1978 at the Seville airport. In this meteorological phenomenon, the air turns around an axis with great force, in a narrow, high swirl. They are very destructive and there was one in the US in 1925, which killed 489 people and destruction of property along 352 kilometres. They usually form in groups and formations have been described as of up to 37 tornadoes in one day.
Waterspouts. They are called this due to the prolongation in the form of a tube of clouds of up to 200 metres high, which is situated between the base of a cumulonimbus and sea surface. They usually last half an hour, but its effects are devastating. They were very feared by old sailing ships that used to fire cannonballs, without much efficiency, in an attempt to disperse them. They are typical of warm waters and in the Mediterranean they sometimes occur. Balearic fishermen call them “fiblo” or “sting”.