WEATHER PHENOMENA IN TENERIFE 2

Weather Phenomena in Tenerife (2) is the second article in a series of six that cover specific weather phenomena in Tenerife and, by extension, the Canary Islands.

What is the weather like on Tenerife, an island of barely 2,035 square kilometers? The answer is not simple, and certainly cannot be explained in one sentence. The island has such a diverse topography that you need several weather types to describe the conditions at the same time. In Weather Phenomena in Tenerife 2, we discuss the dust concentrations that settle over the Canary Islands, known as CALIMA.

To define the weather, we must divide the island into several zones. North and south are already two well-known zones, and west and east also have different focal points. Above all, the Teide and the surrounding mountain zones stand out as an exceptional meteorological area. But you already knew that.

No extremes

In Tenerife, and by extension the Canary Islands, more meteorological phenomena can occur. The location of the Canary archipelago on the subtropical 30th parallel north has more in store than 300 days of sunshine per year.

The Canary Islands have a fairly consistent climate, maintained by the surrounding Atlantic Ocean. Sea temperatures between 19 and 24 degrees Celsius ensure that coastal temperatures rarely exceed 22 degrees in winter and 27 in summer.

Calima

Of course, there are also days when it gets warmer than usual. Extra warm air sometimes seeps in from the east or southeast at higher altitudes and penetrates the archipelago. This is often accompanied by less clear weather. In summer, temperatures can rise by about 4 to 5 degrees, while in winter the difference is barely noticeable. We then speak of a light calima, or calima ligera, as the Spanish weatherperson calls it.

For a real strong calima, more is needed! Barely 300 km away lies the coast of Africa. Sand and dust storms regularly plague the Sahara. With sufficient pressure differences between the Azores High and a so-called thermal low-pressure area over Africa, the wind from the east to southeast can increase significantly. Not only at sea level, but also at higher altitudes, a bone-dry airstream blows from the North African dust belt towards the Canary Islands. Dust, not sand as many might think, blows in from Egypt, across Libya, Tunisia, Algeria, Morocco, Mauritania, Mali, and especially from the Western Sahara. Weather Phenomena (2) – Calima is no joke.

Amount of dust in the air

At altitudes of 2 to 3 km, and sometimes even higher, a large amount of superfine dust is carried by this very warm and dry wind. The inversion typical of this area ensures that it usually doesn’t rise higher than a few kilometers. A beige to reddish-brown dust layer over the sea is the first consequence. The sun is visibly weakened, and with the strong wind, the layer quickly spreads westward.

The eastern islands, Lanzarote, Fuerteventura, and La Graciosa, are hit first with rising temperatures and dropping humidity within a short time. Often, the other islands follow a day or two later. Sometimes La Palma escapes it. Visibility usually decreases to 2 to 5 km. Visually, it’s broadly comparable to haze. In very extreme cases, visibility can drop to a few hundred meters. One calima is clearly not like the other, which is why Spanish meteorologists work with gradations based on the “dust concentration per cubic meter.” These concentrations are measured in Tenerife in Izaña and Santa Cruz with highly sensitive equipment. The amount of dust in the air is expressed in µg/m³ (micrograms per cubic meter) and divided into several categories. The European information threshold is 180 micrograms per cubic meter. Computers mainly calculate its movement over the short and medium term.

Warmer than normal

Besides the bothersome dust, a temperature increase also affects the human body. When the calima suddenly lands with a rising east-southeast wind, temperatures in the summer often increase by 6 to 10 degrees in just half an hour. It can be well over 30 degrees in the early morning instead of the usual 20 to 22 degrees. But don’t be surprised if the mercury rises to 35 or 40 degrees. Once, the temperature in Tenerife reached 44.3 degrees, the highest shade temperature ever recorded on August 17, 1988.

The temperature pattern is highly dependent on wind direction and speed. When the strong easterly wind stops, the temperature often drops again. Extreme temperature fluctuations, lots of dust in the air, and humidity levels often below 20% are not healthy and make it unbearable for people with lung and heart problems. Breathing problems among at-risk groups lead to an influx of emergency room visits.

Unpredictable

The calima has a very unpredictable nature; it can end after half a day, or sometimes last for a whole week. The average duration is 3 to 5 days. Afterward, the temperature and humidity return to their normal levels. Weather Phenomena (2) – Calima can occur year-round but is slightly more frequent in spring and summer.

If you’d like to check how dust concentrations move across the North African dust belt, you can see it HERE. You can read part 1 of this series HERE.