Sunday Telegraph from London, Greater London, England • 35

Farmers who reap what they see in the stars HOW PREDICT THE klVwt We untke ci nJt vtr a nvfstkry oW we Aetr aZ? lar success of the potato farmers in 1973 while studying in Peru During the festival of San Juan in late June each year local farmers scrambled up to the top of the nearest mountain and scoured the horizon for the Pleiades the famous star cluster in the constellation Taurus sometimes called the Seven Sisters After studying its appearance the farmers would ponder the omens and return to their fields planting their potatoes according to what they had seen According to folklore if the Pleiades looked especially radiant four months later there would be plentiful rainfall and a good harvest If the Pleiades appeared lacklustre and faint little rain would fall later in the year making early planting essential Prof Orlove and his colleagues quickly focused on one possible explanation: that the farmers had found a way to predict the effect of El Nino the notorious warm current in the Pacific Ocean which triggers climatic upheaval worldwide Studies of weather records in the area duly confirmed that rainfall is much lower in those years when El Farmers often lament how clueless people are these days about where their food comes from As a townie I must admit that I had no idea harvest festival was approaching until I heard how churchgoers in Gloucestershire had been banned from donating tins of baked beans because vicars just give them away I been to a harvest festival in years but I recall finding the ceremony a bit quaint with its hymns and sermons expressing relief that all had been safely gathered in ere the winter storms begin It seemed to hark back to an age when farmers were utterly at the mercy of the elements They still are to a large extent of course: even satellites and computer forecasts cannot give farmers warning of weather months ahead Even so long-range forecasts are clearly better than all the mumbo jumbo that farmers relied on years ago: weather that comes in with the moon stays like it for a and similar nonsense Farmers in the Andes of Peru and Bolivia still insist on planting their spuds only after consulting the heavens first This agrarian astrology would be cause for a smug grin were it not for the fact that it is stunningly effective predicting rainfall months in advance more reliably than any scientific method Or rather any other scientific method According to Prof Benjamin Orlove of the University of California these Andean farmers have tapped into a genuine natural phenomenon with extraordinary predictive powers In a fascinating paper in the current issue of American Scientist Prof Orlove explains how he first heard of the stel- triggered by El Nino is not clear but it is unlikely that the potato farmers fret about this lacuna in meteorological knowledge What is clear is that their centuries-old ritual works and that scientists could do worse than leave their supercomputers for a while and see what else they can learn from those with a first-hand knowledge of the workings of nature was somehow affected by El Nino The most obvious culprit is increased cloud cover but this idea quickly runs into trouble First as El Nino years bring less rain to the area the Pleiades should surely be clearer when the ocean current strikes not fainter as the folklore insists More importantly clouds are fickle and could hardly be used to pre altitude clouds too thin to see yet dense enough to affect starlight It proved to be the key After trawling through satellite data Prof Orlove and his team found that during El Nino years there was indeed an increase in high-altitude clouds in the region during late June and in precisely the part of the sky where the Pleiades appears Quite why such clouds are dict rainfall four months ahead Less determined scientists or more arrogant ones might well have given up dismissing astrological crop-planting as a silly myth A discussion with a meteorologist at the University of Maryland put the team back on track Dr Gene Rasmussen suggested that the farmers might be witnessing the effects of high- Nino appears threatening lower potato yields Yet how could the appearance of a star cluster 400 light years away be linked to an ocean current? A clue came from the farmers themselves who placed great import on the brightness and number of stars in the cluster This led Prof Orlove and his colleagues to wonder if the transparency of the night sky Sometimes you have to grasp at straws to keep your children amused points of light the jitters are small compared to the size of the object and do not have so pronounced an effect Seen through a telescope however the effects of the turbulence appears as quivering around the edge of the disc of the moon and planets One of the biggest recent advances in astronomy has been the development of which cancel out the effect of turbulence By constantly flexing the mirror of the telescope under atmosphere which triggers random jittering in the rays of light from celestial objects The size of these jitters varies with local conditions such as heat from homes and offices but even at the best observatories on top of mountains they are still far larger than the point-like image of stars This makes the stars appear to dance around slightly in other words to twinkle With the Moon and planets which are far closer and thus do not appear as mere quickly re-filled by water pushed up by atmospheric pressure Amazingly enough the resulting column can stay intact and flow upwards to heights of more than 30 feet before descending again Why the moon and planets twinkle the way that stars do? Brian Fuller via e-mail Twinkling or scintillation to use the pompous scientific term is caused by turbulence in the effect so intriguing is the way the liquid continues to flow without any mechanical aid The best way to understand how this is possible is to think of the water in the straw as a fine chain draped over a peg If one end of the chain is lower than the other gravity can drag the rest of the chain over the peg In the case of a siphon the sucking creates a vacuum so that the atmospheric pressure at the other end of the straw can push the water up and over the top of the bend Gravity then does the rest with air pressure keeping the column of water intact If it does try to break apart the resulting gap would contain a vacuum which is computer control the result is an image as good as one taken with a telescope in space (and as a bonus it is about £1 billion cheaper) My grandmother says electricity can leak out of empty power sockets and Insists on switching them off she wasting her time? Julie Johnson via e-mail Your grandmother is right to think that electricity can flow through air buf unless her house is wired up to a million-volt supply she need to worry about leaking sockets In normal conditions air is a very good insulator and it takes huge voltages to persuade even a small stretch of air to carry an electric current What we should all be more concerned about are sockets with appliances left plugged in Many of them such as televisions and computers continue to draw small amounts of electricity even when they seem to be switched off keeping them in or allowing bits of circuitry to tick over Each of them may consume only a few tens of watts but as there are millions of them it all adds up: a recent American study estimated that appliances left plugged in when consume about a billion dollars of electricity a year As water cannot travel uphill how does a siphon persuade water to propel itself upwards through a pipe without any mechanical help? George Vale via e-mail often had cause to exploit the siphon effect chiefly in cafes as a means of amusing my offspring while waiting for their meals to arrive If you use one of those bendy drinking-straws with the shorter end stuck in a glass held above another glass sucking on the lower end of the straw sets up a stream of fizzy liquid flowing up and out of the higher glass and into the other in defiance of the law of gravity What makes the I KEEP MY PAYMENTS THE SAME AND SAVE £10000 ON MY M0RTGA6E NEW! EXPLORE TVS'! open 14th-22nd -look your visit by the I J3th pip no 200 DV 13th SEPTt SW ML NEW! FLY-A- HOV POD FREE the coolest craft on water or land HM COASTGUARD RESCUE real life heroes show how it's done SPECTACULAR MARiNA! Europe's biygest purpose-built show marina NEW! WAVE 105 WATERSP0RTS ZONE live your dreams IB! Hr i ffli BY USING MY INTELLIGENCE How? 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