söndag 29 januari 2012
The last few days the lakes of Skåne have frozen to allow ice-skating, and for the keen CAnMove co-ordinator Susanne Åkesson and development engineer Arne Andersson this is an opportunity that cannot be missed. On the photo they can bee seen skating leisurely in tailwind along the south shore of Krankesjön, some 20 km east of Lund, both outfitted in smart long-distance skates of top-brand. They could experience the real effect of wind, as they had to go back along the north shore of the lake in a moderate head-wind to make the roundtrip, which caused them to reflect about how winds affect migratory birds. Another analogy between skating and bird flight is the relative ease by which humans can traverse distance on skates at a relatively low cost, as compared with for example walking/running, crawling or swimming. The analogy is with the lift to drag ratio of flight, a measure on the efficiency of locomotion, which the ice-skating CAnmOve reps out on the ice felt as relatively high. The ice was perfect today (see picture), and hopefully it will remain so for some more time.
tisdag 17 januari 2012
A new study published in the current issue of Science reports about climate change related effects in flight behavior in wandering albatrosses, breeding on Crozet Islands in the southern Indian Ocean. Due to climate change related phenomena the mean wind speed has increased in the southern oceans, between 50 and 60 S. Albatrosses use dynamic soaring, which is a way of extracting energy by soaring in the wind gradient in the boundary layer of the sea. The stronger the wind, the faster the albatrosses can fly. A french team, lead by Henri Weimerskirch, has studied wandering albatrosses on the Crozet Islands during 20 years. During this period the winds have increased, and the scientists have been able to measure related properties in the albatrosses. The albatrosses now forage further to the south, their flight speed has increased from 10 to 12 m/s, and their daily travel rate during foraging journeys has increased from 500 to 700 m/s. Better foraging success has led to improved breeding success, and the albatrosses have increased by about 1 kg in body mass. It seems as if we here have a positive effect related to the ongoing climate change, but the scientists mention that the predicted scenario of wind change will come to a deterioration further down the trail, so the observed effects may be temporary. It is very nice, though, to see a study reporting an association between climate change and flight speed.