The distribution of rainfall intensity in Israel, its regional and seasonal variations and its climatological evaluation

A large body of data has been used to study the distribution of instantaneous rainfall intensity in Israel and its variations in space and in time. Time resolution is ±3 minutes. Besides the direct uses that the numerical results may have for practical purposes, the results have been used here to characterize rainfall in a climatologically more meaningful way. This includes reference to the atmospheric processes and surface‐conditioned effects that influence rainfall formation, and the identification of regional and seasonal variations in these processes. Thus, it has been shown that contrary to prevalent views, orographic rainfall in Israel is characterized by low intensity, apparently resulting from a continuous advection of moist air through a zone of gradual topographically forced uplifting. In the presentation of results, emphasis has been put also on the significance of results from the point of view of rain‐conditioned processes occurring on the earth surface, such as in hydrology, geomorphology, etc. In this context, the water yield from high intensity rainfall has been shown to reflect a high degree of concentration, both areally (through convergence in the atmosphere and run‐off processes on the ground surface) and in time (in warm seasons and in certain parts of the day). These features, as well as the relative frequency of high‐intensity rains itself, has been shown to be more pronounced in the arid Negev than in the more humid parts of the country. This explains at least in part the increased uncertainty characterizing rainfall in the arid zone.