Starting with the deliberations of the Greek philosophers 2500 years ago, but delayed firstly by Roman indifference to the Greek tradition of academic enquiry, followed by the suppression of secular thought by the church through the next 2000 years, then revived by the Enlightenment in Europe and refined by the scientific revolution of the last few hundred years, we have finally arrived at a thorough understanding of the processes leading to precipitation. There are some areas that still need refinement, such as better insight into a number of aspects of lightning, into the growth of snow crystals and the dynamics of some clouds, but otherwise our understanding of the processes involved is reasonably complete.

For the future, new and different tasks have arisen in the wake of these past achievements. Firstly there are still many old raingauge records that have not yet been collected together and assembled into datasets, but there is plenty of vibrant activity in progress compiling, gridding and analysing these data at the world's leading government and academic research centres. The measurement of precipitation, on the other hand, lags far behind.

The first known ‘scientific’ measurement of rainfall was made by Castelli in 1639 in Italy, followed soon afterwards by Sir Christopher Wren and Robert Hooke, among others, in England. Over the next 450 years improvements were made to raingauges and to how they were exposed, but progress was relatively slow and precipitation measurement has not kept pace with our greatly improved understanding of the processes of precipitation.