This volume is the condensation of lectures given to students at Imperial College Department of Meteorology, while it existed, and to students of Environmental Science at the University of East Anglia when the department at Imperial College was closed down. Any good sense it might contain is almost certainly attributable to colleagues. Eric Eady opened my eyes to many fascinating phenomena, though when I taught students I began to realise that such communication is perhaps more of a two-way process than I imagined at the time. It is one thing to speculate on an interpretation, but another when this stimulates a response. Recalling a technical difficulty to a non-technical partner is perhaps a simple illustration of the suggested interaction. There is also a lot of Frank Ludlam here. He asked for explanations of mathematical theories that he could understand without having to go through the detailed mathematics. I remember an early encounter when he described his method of evaluating integrals. Simple, he said, ‘you just move the variables, one by one, through the integral sign ’till you are left with an integral that you can do’. Aspects of this collaboration can be seen in his book on Clouds and Storms, which has some of me in it, but which for political reasons was forgone; Frank died before his wonderful book was published. The philosophy here is almost all that of Professor Peter Sheppard, who tormented, teased, threatened, sometimes disillusioned, many generations of students, for his criticisms were accurate and acid.