WE meteorologists really get around, you know. One day last week I found myself in Geisenheim, a small town in Germany not far from Frankfurt. It is home to two institutes intimately connected with viticulture: the Geisenheimer Forschungs-anstalt, which carries out research into the culture and breeding of the grape, and the Geisenheim Agrometeorological Institute which provides weather advice to vignerons throughout the Rheingau wine-producing region.
The Rheingau is the area where the famous Riesling wines originate. It lies on the 50th parallel, often considered to be the most northerly latitude at which viticulture can be contemplated with equanimity, but enjoys a particular advantage because of a sudden sally of the Rhine in that vicinity.
The river, as we know, flows generally from south to north; just east of Frankfurt, however, it turns sharply left, and for a short distance between there and Bingen it runs from east to west. As a consequence, the slopes of the now northern river-bank face south - if you still follow me - and gather more sunshine than virtually anywhere else along the river.
Ground that slopes south-wards towards the midday sun receives much more radiant heat per unit area than level ground; in the latter case, the sun hits the ground obliquely, and the same "bundle" of rays is spread over a larger area than if the surface were inclined to accept the impinging radiation at right angles.
As a rough rule, a south-facing surface with a slope of 45 degrees gets about 50 per cent more energy than horizontal ground. Hence, despite its northerly location, the Rheingau region produces very fruitful vines indeed.
As I tasted a dozen or so varieties of Riesling - all in the line of duty, don't you know - I was reminded of an economist who once tried to relate the quality of wine to the weather. Not being a connoisseur himself, our dilettante decided - appropriately enough for an economist - that price was the best historical indicator of quality.
So by studying the records of wine auctions, he was able to discover which were the most expensive years, and therefore, presumably, the best. Weather statistics were then fed into a formula which provided a "quality index" for each year, and thus a "buyer's guide" as to which vintages were worth acquiring, and which ones to avoid.
The cognoscenti of the wine world, naturally, sniffed dismissively. Their attitude to the cheeky parvenu was reminiscent of James Thurber's introduction to a less than favourite vintage, "a naive domestic Burgundy without any breeding, but I think you'll be amused by its presumption".