Lewis Fry Richardson dreamt that scientific weather prediction would one day become a practical reality. Before his ideas could bear fruit several advances were needed: better understanding of the dynamics of the atmosphere; stable computational algorithms to integrate the equations; regular observations of the free atmosphere; and powerful automatic computer equipment. By 1950 advances in all these fronts were sufficient to permit the first computer forecast to be made. Over the ensuing fifty years progress in numerical weather prediction has been dramatic. Weather prediction and climate...