Word spreads quickly when the Irish Meteorological Society has a lecture planned, even over here to Germany. One of the highlights of the Dublin intellectual season will take place tonight when Francis Wilson talks about hotair ballooning. Both he and his topic are very much in evidence to exiles in partibus infidelium such as I.
Francis Wilson, as everybody knows, is an English television weatherman. He is also a frequent and, it must be said, a very polished presenter of the weather forecast on Sky News, which is one of the few points of contact with the English-speaking world for Anglophones in Germany. Over here, I watch him almost every night.
But balloons in these parts are also very a la mode. Every Sunday brings them out, not just one or two, but several, maybe even half a dozen, floating gently and colourfully with the wind, strung out like bunting to decorate a quiet autumnal sky. Wind of any consequence in the Rhine valley is unusual, which makes the sport more viable than in Ireland's blustery regime.
The importance of the wind is not that it affects the speed at which the craft proceeds when airborne, but rather the difficulty it presents during the process of inflation. A breeze of more than about 10 mph makes the 10 ft flame that generates the necessary heat difficult to control and as a result the nylon fabric may be damaged. Moreover, a partially inflated balloon quickly assumes the dimensions of a large building, and may - quite literally - get out of hand in a strong wind. And, of course, once in the air, sooner or later a balloon returns to earth, and a soft landing is difficult to achieve in a laundry basket at 40 mph.
Temperature is also important. On a very hot day with a temperature of say 25C, the air inside the envelope may have to be heated to over 100C to lift a heavy payload; this heat may be more than the fabric of the craft can stand. And even "thermals", those rising currents of warm air so beloved of glider pilots, are viewed with apprehension by balloonists; they cause erratic ups and downs which make it hard to execute a well-controlled and comfortable flight.
Unfortunately, I will be there only in spirit tonight in Theatre G33 of the UCD Earlsfort Terrace complex. But anyone who lives a little closer to the venue is welcome at 8 p.m. to hear what will undoubtedly be a most informative and entertaining talk .