Simulation and Understanding in the Study of Weather and Climate

In the study of weather and climate, the digital computer has allowed scientists to make existing theory more useful, both for prediction and for understanding. After characterizing two sorts of understanding commonly sought by scientists in this arena, I show how the use of the computer to (i) generate surrogate observational data, (ii) test physical hypotheses and (iii) experiment on models has helped to advance such understanding in significant ways.