Wednesday, August 4

The terral “goes through neighborhoods”: the hot wind that hits Malaga and causes differences of 10 degrees


On the coast of Malaga there are few meteorological phenomena more feared than the wind that comes from the northwest, loaded with scorching heat, called terral. From one moment to the next, the relatively cool temperature given by the sea breeze turns around, and the place turns into hell on earth. The land frightens the Malaga, fearful of a wind that dries everything, even the spirit. Something like this happened this Monday and it happens several times a year.

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In 2020, the terral was able to raise the thermometer in Vélez-Málaga more than anywhere in Spain, up to 45.7 degrees last August 2. Nothing to do with the relatively mild temperatures of the province in the hottest months. That day, the province registered nine of the ten highest temperatures in the country, all above 40 degrees. However, the terral is usually very selective: a wind capable of scorching a town and leaving the one next to it alone. That day, Marbella did not exceed 34 degrees while neighboring Estepona reached 44. Experts say: “The terral goes through neighborhoods.”

Several factors influence the fact that the phenomenon is very localized, to the point of causing temperature differences of up to ten or twelve degrees six kilometers away.

“It is difficult to see such striking differences as in Malaga”

He says Glossary of the State Meteorological Agency that the terral is the breeze that blows from the land to the sea when the land surface cools faster than the sea surface, which better preserves its temperature. In Malaga, a Mediterranean and southern province, this wind comes from the north through the Guadalquivir Valley and the Guadalhorce Valley, where it overheats, until it surpasses the last mountains and drops abruptly to the sea.

In spring-summer, these “katabatic winds” cause the air mass “when descending to leeward” from the mountains near the coast, to heat up and dry out by compression, “sometimes reaching very high temperatures and very low relative humidity”, technically explains AEMET. The same winds in winter bring the cold, but that’s another story.

This is what happened this Monday, with maximum temperatures that were around 40 degrees in part of the province. However, the orographic conditions and its extreme link to the wind mean that the distribution of heat is far from being uniform. For example, in Estepona the maximum on Monday was 38.6 degrees (at 3:30 p.m.), while in Marbella, the next coastal municipality to the east, the maximum was 32.5 degrees. At the same time, the temperature was almost eight degrees lower.

This phenomenon occurs very markedly in various parts of the province. It is enough to walk the Mediterranean highway one day in the terral to observe a sharp drop in temperatures as it passes through Algarrobo, in the Axarquía. The descent sometimes reaches ten degrees in less than ten kilometers. “It is difficult to see such striking differences as in Malaga,” he concedes José María Sánchez-Lauhlé, director of the Malaga Meteorological Center.

Terral factors: river beds and exposure to the west

The inland orography of the land and the orientation of the coastline explain the phenomenon. The wind takes advantage of the river beds and valleys (generally dry at this time of year) to descend. They work like a highway: the rivers channel, heat and distribute the air. For example, in Vélez-Málaga it enters through the Vélez river and to Málaga through the Guadalhorce valley.

In addition, the layout of the coast exposes some areas to the marine influence of the winds from the Strait as soon as there is a slight component from the west, while others are “hidden”. “It is easier for the terral to enter places that do not have an exit from the river or an entrance from the west”, Sánchez-Lauhlé illustrates. The influence of the Strait reaches less to the bay of Estepona or Malaga, in more concave areas of the coastline. On the other hand, points like Marbella or Algarrobo receive the west wind much more directly.

Another factor is the distance to the coast from the meteorological station to the coast point, but in this case the differences are not excessive: the airport (usual point of reference for the capital) is 3.3 kilometers in a straight line, the station from Vélez to 3.7 and that of Algarrobo to 1.3.

All these factors explain that there is hardly any difference between the temperatures recorded by nearby meteorological stations under normal conditions, but that they can reach double digits on terral days. If there is no terral, the differences are around two or three degrees. But if the dreaded north wind hits, the difference shoots up to ten degrees or higher.

For example, on July 6 (penultimate day of terral) a maximum of 38.1 degrees was reached in Vélez-Málaga, while six kilometers in a straight line, at the Algarrobo station, it only reached 29.4. This Monday afternoon the terral did reach Algarrobo for a while, but it passed quickly: from six to eight the temperature rose from 29.3 to 37.9, but at nine at night the situation had returned to normal: 28 , 8. On the other hand, in Vélez-Málaga the temperature did not drop below 36 degrees from noon to ten at night, with a peak of 41 at five in the afternoon. At that time, in Algarrobo the temperature was 29.7 degrees, 11.3 degrees less.

Differences of 13 degrees in the capital

“The difference between Algarrobo / Torrox Costa and Vélez-Málaga is brutal,” he says. Jose Luis Escudero, passionate about meteorology who feeds the blog Storms and Lightning, in Diario Sur. Escudero highlights that the terral goes through neighborhoods. When it is pure terral, it can affect the entire capital and even reach Rincón de la Victoria, going down through the streams. But when it is a “terrified west”, it has seen differences of 13 degrees within the capital. Something similar comments Sánchez-Lauhlé, who travels every day from El Palo (a fishing district east of the capital) to the airport, three kilometers from the coastline.

Escudero, a retired department store employee, is a meteorologist by vocation. For next year he wants to write a book about the terral. After all, he says, it also has good things. For example, it leaves the sea very cold, as the surface waters move towards Alboran and the deep waters of the Mediterranean emerge. This upwelling phenomenon refreshes temperatures throughout the summer.

In addition, Escudero values ​​that, unlike what happens with the east wind, with the terral there is no sweat: “If it’s 37 degrees, it’s 37.” And if there are 45, like last year in Vélez-Málaga, it will always be possible to move a little, if only to escape the heat.



www.eldiario.es

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