An Almanac, Not An Index
2024-06-11
In 1921, Lewis Fry Richardson wasn’t satisfied with the current state of weather forecasting. His criticism of the paradigm was fundamental: it relied on pattern-matching instead of modeling the physics of the atmosphere. In the preface of his book Weather Prediction By Numerical Process, which would go on to revolutionize how meteorologists forecast the weather, he described the dominant approach:
The process of forecasting, which has been carried on in London for many years, may be typified by one of its latest developments, namely Col. E. Gold’s Index of Weather Maps. It would be difficult to imagine anything more immediately practical. The observing stations telegraph the elements of present weather. At the head office these particulars are set in their places upon a large-scale map. The index then enables the forecaster to find a number of previous maps which resemble the present one. The forecast is based on the supposition that what the atmosphere did then, it will do again now. There is no troublesome calculation, with its possibilities of theoretical or arithmetical error. The past history of the atmosphere is used, so to speak, as a full-scale working model of its present self.
Richardson, as well as meteorologists Cleveland Abbe and Vilhelm Bjerknes, wanted to infuse the discipline of meteorology with a more scientific approach. Indeed, Abbe wrote in 1901 that the predictions, “merely represent the direct teachings of experience; they are generalizations based upon observations but into which physical theories have as yet entered in only a superficial manner if at all.”