Tenerife has often been called the island of Eternal Spring - but what does this mean and just how does this description come about? Damian Peach (Award winning Planetary Astrophotographer and Assistant Director of the BAA Jupiter Section) explains the reason for this phenomenon in this extract form his artice The Ultimate Location for Amature Astronomy? published on his web site www.damianpeach.com and also in the journal of the BAA 2004.
Tenerife - The Island & its weather Many readers will be familiar with Tenerife. Not just being the largest of the Canary Islands, it is also visited by millions of tourists from the UK and Europe each year, to enjoy the year round sunshine. The island was forged over millions of years through volcanism, and at the island centre lies the amazing landscape of the Parque Nacional de Las Canadas – a huge caldera ~20 km across, with the 3718m peak of El Teide at its centre. It lies 180 miles off the coast of North Africa, but differs greatly, both geographically and Climatically to its neighbour. Tenerife’s steep local orography creates many micro-climates across the island, and one can almost experience all four seasons in a trip from sea level, into the mountains. The northern windward side of the island is in general cooler at sea level, and suffers much more from clouds due to the frequent onshore winds, and frequent inversion layer. The weather of Tenerife (and the other islands) is governed by the North East trade winds, which prevail over the islands most of the year, and especially during the summer months. This trade winds regime is partially responsible for the presence of a near permanent temperature inversion layer over the area, which is actually a commonplace occurrence across the Earth’s subtropical regions. An “Inversion” refers to the opposite state the atmosphere normally takes (with warmer air located nearer the ground, and cooler air higher up, giving rise to convection.) An Inversion occurs when cooler air is located near the ground, and warmer air, above which suppresses local convection. This effect across the Canary Islands is caused by the trade winds blowing at sea level, and warmer dry air, subsiding above.  Fig01a: A diagram showing the two different states of the atmosphere, and the state is takes when a temperature inversion occurs. Temperatures vary very little throughout the year across the islands; at least at sea level locations across the South side of the island. The North is generally cooler and wetter than the South; especially up on the mountainside. At altitudes of around 1000m and up snowfall can occur along the northern coast during winter, and the Teide itself often presents a wonderful snow covered appearance during the winter months. Around 280 clear nights per year are experienced on the South side of the Island (rather less on the windward northern side), and weather often consists of well broken fair weather clouds, rather than blazing clear blue skies most days. Relative Humidity is often high (65-90%) throughout the year, and rainfall is low, with around 25-30mm in the wettest month (November.) The sea temperatures also vary little throughout the year. |