Clearing the clouds of weather forecasting

In the first chapter of St John's Gospel, Nathanael asks Phillip: "Can any good thing come out of Nazareth?"

In the first chapter of St John's Gospel, Nathanael asks Phillip: "Can any good thing come out of Nazareth?"

The meteorological establishment voiced much the same opinion in the early 1920s, reacting to the novel ideas on the science emanating from Norway. As one eminent German scientist remarked: "How could anything scientifically important come from a tiny, conservative little place like Norway?"

Yet Norwegian concepts revolutionised weather forecasting.

By the time you read this column, Norway, all going well, is precisely where I ought to be. I will be visiting the headquarters of the Norwegian Meteorological Institute, in Oslo, to talk about - what else? - the weather and, in particular, the use of weather satellites in Scandinavia.

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But the roots of meteorology in Norway are to be found across the mountains on the coast of the Atlantic, where the town of Bergen nestles by its fjord. There, 80 years ago, the so-called "Bergen school of meteorology" amazed the world when it unveiled the theory of the polar front.

The impetus behind the Bergen School was Vilhelm Bjerknes, who had spent much of his adult life as a professor in the University of Leipzig. He had a keen interest in meteorology, and in 1917 he returned to his native Norway to establish "an improvised weather service" for the fishing fleet of this maritime nation. In in a small office overlooking the harbour at Bergen, he established a team of quite extraordinary talent.

Within five years the Norwegians had made one of the greatest discoveries in the science of meteorology. Meteorologists had long been familiar with the concept of the moving depression. The progress of these areas of low pressure could be followed on successive weather maps, and it was known that rain was associated with certain sectors of the depression - but the pattern appears to be disorganised.

The Norwegians, however, drew the veil aside to reveal the detailed structure of a mid-latitude depression with brilliant clarity. Drawing on the military terminology from the recent war, they introduced the concept of warm and cold fronts, separating air masses with differing characteristics of temperature and humidity. Once the concept was explained, it was so obvious that people wondered why no one had spotted it before.

The Norwegian breakthrough brought order into the apparent chaos of the weather. Like many new ideas, it took some time to be universally accepted, but by the late 1930s, air-mass and frontal analysis had been adopted by all the major weather services of the world, and it remains the foundation of modern weather forecasting.