The purpose of this research work is the analysis of a number of precipitation events, using the RD-69 Joss-Waldvogel
Disdrometer measurements. This instrument measures the raindrop size distributions continuously and automatically by
transforming the vertical momentum of an impacting raindrop, whose amplitude is a function of the drop diameter. The
range of drop diameters varies from 0.3 mm to 5.6 mm (dividing them into 20 channels). The knowledge of drop size
distributions in rain is of importance in precipitation physics and radar hydrology and is used to estimate various
hydrometeorological parameters, such as rainfall rate R, and radar reflectivity factor Z. Four different equations for the
final falling velocity (V<sub>t</sub>), depending on the diameter, were used and evaluated based on the Z-R relationships.