It is an amazing act of faith that allows glider pilots to have such confidence in the BBC weather forecast, regardless of experience. I live in an apartment overlooking the sea at San Vicente Tenerife during the winter, and on Saturday February 22nd this year, I googled to check that all was sunny and bright as usual. But there was something hazy about the horizon and a faint orange tinge in the air. It was the precursor to the most powerful calima storm that anyone born here can remember. I have experienced some powerful Saharan winds over the years but this was exceptional.
East wind sent tons of sand across the ocean to fall on the Canaries. But sometimes there is an extra hazard to the arrival of the calima. In 2004, the desert storm lifted millions of locusts into the sky and swept them the three hundred odd kilometres across the water to fall on the islands. If you have never seen a swarm of locusts arriving on the beach before, just take my word for it that it can be very disturbing.Their life cycle is short but an interesting one; it goes from egg, to hopper then to full grown locust before death at around six months.
They are solitary at first, but when conditions are ideal for swarming they muster at the launch point, rather as we do on a 500 km. day. Their behaviour and declaration target is always down to the weather. Their aim is to fly with the wind as far away as possible, and then to land in pastures green for a huge meal. As we speak they are wreaking havoc in parts of Africa and the Middle East. When they flew to Tenerife in 2004 they were exhausted and at the end of their normal life span, and did little damage to crops. They are stable in flight and can immediately correct for any possibility of stalling. But the flying characteristics of the individual is different from that of the swarm. Aerodynamacists among our members can read the technical details in a research paper given by: (Taylor and Thomas. Journal of Experimental Biology 2003)
When the winds from the desert abated on this 2020 encounter, I was glad to note the absence of locusts, but there was still a surprise in store. The winds that blew up the barranca Ruiz had brought a different cargo. The Odonata dragonfly had been sighted here in the past, but only in small numbers. Whirling around above the barranca were thousands of them, chasing the insects that are their staple diet. The Odonata is among the oldest surviving creatures on planet earth. They can fly every manoeuvre that a glider can do plus hover and move sideways, with an average speed of around 30 knots they can turn on a sixpence.
By Peter Holloway