Lewis Fry Richardson - Weather Forecasting

Weather Forecasting

Richardson's interest in meteorology caused him to propose a scheme for weather forecasting by solution of differential equations, the method used nowadays, though when he published Weather Prediction by Numerical Process during 1922, suitable fast computing was unavailable. He described his ideas thus (his "computers" are human beings):

“After so much hard reasoning, may one play with a fantasy? Imagine a large hall like a theatre, except that the circles and galleries go right round through the space usually occupied by the stage. The walls of this chamber are painted to form a map of the globe. The ceiling represents the north polar regions, England is in the gallery, the tropics in the upper circle, Australia on the dress circle and the Antarctic in the pit.

A myriad computers are at work upon the weather of the part of the map where each sits, but each computer attends only to one equation or part of an equation. The work of each region is coordinated by an official of higher rank. Numerous little "night signs" display the instantaneous values so that neighbouring computers can read them. Each number is thus displayed in three adjacent zones so as to maintain communication to the North and South on the map.

From the floor of the pit a tall pillar rises to half the height of the hall. It carries a large pulpit on its top. In this sits the man in charge of the whole theatre; he is surrounded by several assistants and messengers. One of his duties is to maintain a uniform speed of progress in all parts of the globe. In this respect he is like the conductor of an orchestra in which the instruments are slide-rules and calculating machines. But instead of waving a baton he turns a beam of rosy light upon any region that is running ahead of the rest, and a beam of blue light upon those who are behindhand.

Four senior clerks in the central pulpit are collecting the future weather as fast as it is being computed, and despatching it by pneumatic carrier to a quiet room. There it will be coded and telephoned to the radio transmitting station. Messengers carry piles of used computing forms down to a storehouse in the cellar.

In a neighbouring building there is a research department, where they invent improvements. But there is much experimenting on a small scale before any change is made in the complex routine of the computing theatre. In a basement an enthusiast is observing eddies in the liquid lining of a huge spinning bowl, but so far the arithmetic proves the better way. In another building are all the usual financial, correspondence and administrative offices. Outside are playing fields, houses, mountains and lakes, for it was thought that those who compute the weather should breathe of it freely.” (Richardson 1922)

(The word "computers" is used here in its original sense - people who did computations, not machines. "Calculator" also referred to people at this time.)

When news of the first weather forecast by the first modern computer, ENIAC, was received by Richardson during 1950, he responded that the results were an "enormous scientific advance." The first calculations for a 24 hour forecast took ENIAC nearly 24 hours to produce.

He was also interested in atmospheric turbulence and performed many terrestrial experiments. The Richardson number, a dimensionless parameter of the theory of turbulence is named for him. He famously summarised turbulence in rhyming verse in Weather Prediction by Numerical Process (p 66):

Big whirls have little whirls that feed on their velocity,

and little whirls have lesser whirls and so on to viscosity.

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