Abstract
Analysis has been made of three winter rainstorms, resulting from large-scale uplift, in which the generating level and the precipitation mechanism were essentially constant. The data show that the ground-level Sr90 concentration in the precipitation is determined by the descent experience of the precipitation in falling from the, generating cloud to the ground. The descent experience, can be expressed in terms of the height of the ceiling, which is an index of the humidity profile and depth of the lower layers of air. These parameters affect the rate of evaporation or growth of the precipitation elements and, thus, the final concentration of Sr90 reaching the ground.
