Research themes Climate change: the role of clouds, rainfall and aerosols in the climate system Measuring the atmosphere Climate engineering Nowcasting rainfall Research I am fascinated by the observation-and-interpretation process. Most observations we do - whether scientific or social- are indirect: one never measures the meaning directly, but needs assumptions and models before the interpretation can be made. This is also true for remote sensing. The direct measurement is often expressed in terms of energy or power, but what one wants to know is: how much rain is falling?, or how do aerosols change clouds? This requires a good understanding of the underlying physics, the observation technology and of signal processing. It truly needs a multi-disciplinary approach.