Meteorological systems producing rainfall

The knowledge of the rainfall spatiotemporal distribution is of utmost importance for many applicative problems. At mid-latitudes, frontal disturbances give a substantial contribution to the rainfall depth in the autumn and winter periods, producing the maximum annual rainfall depths of long durations and frequently heavy floods, which require an appropriate warning. An analysis in depth of the main processes involved in the generation of rainfall ahead of, on and behind a front passage at the ground level is provided on the basis of investigations earlier performed in the British Isles. Particular emphasis is given to the interaction between frontal systems and orography. A diagnostic model that relies upon the formulation of the widely recognized seeder-feeder process is also described. Finally, the application of the model to two warm frontal disturbances observed in an inland area of Central Italy is discussed.