WEATHER LORE

TENERIFE

Just 300 km off the west coast of Africa lie the Canary Islands, an increasingly popular destination for both holiday makers and people in search of a ‘place in the sun’.

The largest and most populated of the islands is Tenerife, around 7,500 people live on 2000 square kilometres. This may sound like a large area, but consider this; 2000 square kilometres is only equivalent to an area 40 km wide by 50 km from north to south!

Tourists are attracted by the climate. Tenerife is called the island of ‘Eternal Spring’, being very close to the Tropic of Cancer it averages 20 Celsius in January and around 24 Celsius in summer.

This almost monotonous climate is caused by its location within a trade wind belt of steady, reliable winds and ocean currents.

It’s said that sub-tropical places such as this have only climate, not weather, but average figures mask variations and microclimates uncommon for such a small island.

The greatest difference exists between the north of the island and the south. Although only 40 to 50 km apart the two coasts, north and south, are separated by Mt Teide; at 3718m this peak is the highest in Spain, often snow capped, it is also a dormant volcano that erupted as recently, in geological terms anyway, as 1909.

Most tourists head for the semi-arid south coast around the resort of Los Christianos. This area lies in the so called ‘rain shadow’. The prevailing northerly wind brings rainfall to the north of the island as the air rises up the slopes of Mt. Teide, but by the time the air descends the southern slopes of the mountain it is both warmer and drier than it was in the north.

This is exactly the same rain shadow effect that causes the difference in rainfall in this country between Manchester to the west of the Pennines and Lincolnshire to the east.

The effect is just more pronounced on Tenerife. The north of the island has dense vegetation, forests and banana plantations …..

…… whereas the southern, leeward side of the mountain is a semi-arid landscape of bare soils and barren, rocky slopes.

There is a downside to this climatic quirk, however, as increased tourist numbers in recent years have put a massive strain on the island’s water resources. The low annual rainfall and the fact that up to 75% is lost be evaporation and runoff mean that they are reliant on underground water supplies. Perhaps a new ‘water tax’ should be added to existing tourism and environmental taxes!