The Calima

One of the most interesting natural fenomens on Gran Canaria is the Calima. The hot wind from sahara brings small dust particles over the the 150 kilometers of ocean and settle on Gran Canaria. Other than pushing up the temperatures to 40 degrees celsius and Calima is also responsible for the wonderfull sandy beaches of the south.

The Calima usually lasts for 2-7 days, and is present in the summer parts of the year. Once the Calima is present, it will cause lessening of visibility due to the particles it carries, bring temperatures up, and also might couse respiratory problems if you are suffering from astma or bronchitis. If you do not have problems with that, you will be just fine. The natural fenomen causes some very interesting sunsets due to the particle concentration if the air and the clouds. Calima can stop very suddenly if rain is introduced or the direction of the wind changes.

The fine sand particles cause the air to become thick, and visibility becomes rather like that experienced during a thick fog. During the calima, every surface will be covered in fine reddish brown dust.

Officially the Calima is called The Saharan Air Layer.

The Saharan Air Layer

The Saharan Air Layer - Calima - over the Canary Islands

The Saharan Air Layer (SAL) is a dry, warm and usually dust and sand layer of the atmosphere which often overlies the cooler, more-humid surface air of the Atlantic Ocean originating from the Sahara Desert region of North Africa. It can be high up to 6 kilometers, as it flows over the ocean lifted by the lower, denser marine air.

Large thunderstorm complexes over North Africa periodically result in dust and sand storms, which can be driven out to sea within the SAL as far west as North America.
In the case of Africa, winds blow 20% of dust from a Saharan storm out over the Atlantic Ocean, and 20% of that, or 4% of a single storm’s dust, reaches even the western Atlantic. The remainder settles out into the ocean, or washes out of the air with rainfall.

Research shows that the iron-rich dust particles which often occur within the SAL reflect solar radiation, thus cooling the atmosphere. The particles also reduce the amount of sunlight reaching the ocean lowering the amount of heating of the ocean. It increases condensation as it drifts into the marine layer below, but not precipitation as the drops formed are too small to fall. These tiny drops are subsequently more easily evaporated as they move into drier air laterally or dry air mixes down from the SAL aloft. Research on aerosols also shows that the presence of small particles in air tends to suppress winds. The SAL has also been observed to suppress the development of tropical cyclones, which may be related directly to these factors.

The Saharan Air Layer is a subject of further research.

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