Being Brits, we’re never short of something to say about the weather and it often involves declaring official forecasts rubbish and deciding that the most accurate way to predict the day is simply to step outside.
Here on Tenerife, because the island has such a marked height to surface area ratio, we have the added complication of micro-climates to contend with which can often make a nonsense of weather reports for the island as a whole. But micro-climates aside, why is it that the official temperatures given on weather stations rarely reflect the numbers you record on your patio?
Thermometers have come a long way since Galileo first invented his thermoscope which measured the heat of the outside air by recording the density of water in a tube which changes with the outside air temperature. Largely used as ornaments nowadays, Galileo’s thermoscopes are not accurate enough to give a proper scale measurement. But even using a good quality thermometer, there’s more to getting a temperature reading than meets the eye.
The first thing to know is that official temperatures are not taken by a thermometer stuck on the wall of the living room, the terrace or the garden shed. In order to get an accurate reading of the current air temperature, the thermometer should be placed away from direct sunlight, away from buildings and at a height of 4ft off the ground over a grassy area.
When a thermometer is placed in direct sunlight, the temperature recorded is that of the glass bulb holding the mercury, heated by the rays of the sun. Official weather stations use weather boxes in which to house their thermometers. The boxes have air vents for circulation and maintain shade 24 hours a day. If the thermometer is placed near any building surface, the temperature recorded is affected by heat given off by the concrete/bricks/breeze blocks or whatever else it’s located on.
The next thing to realise is that official weather stations don’t just record the air temperature so that we know what to pack before we head off on our holidays, that’s just a useful by-product. One of the most important reasons for measuring air temperatures is to record changes in air pressure which help to predict weather changes so we know when to expect rain, or a storm. For that reason, you’ll often find weather stations alongside airports so traffic controllers know what conditions to expect.
If you want to get as close to an accurate picture as you can of the real air temperature on Tenerife, AEMET (the Spanish met office) has stations dotted across the island that will give you an idea. The most useful ones for holidaymakers are in Puerto de la Cruz, Adeje (for Costa Adeje), Arona (for Los Cristianos and Playa de Las Americas), San Miguel (for Golf del Sur and Costa Silencio) and Granadilla (for El Médano) but even then, they are largely sited a few hundred metres above sea level, not on the coast. So if you want a really accurate reading for how hot it is on the beach, step outside.
Category : about tenerife
Subscribe : RSS 2.0