Fraile, Roberto (Universidad de Leon. Spain)
Sßnchez, Jose Luis (same affiliation)
Castro, Amaya (same affiliation)
Marcos, Jose Luis (same affiliation)
Since 1990 the Laboratory for Atmospheric Physics at the University of Leon has made use of a network of 250 hailpads spread over an area of 1,000 km2 in the province of Leon (Spain). By the end of 1995, the network had detected during the summer months 25 hailfalls of more than 15 km2 in area. These precipitations, registered on 13 different days, were generated by the most intense storms recorded in the study zone during the last six years.
The 25 hailfalls were precipitated over more than 300 hailpads, leaving nearly 40,000 measurable prints. By means of the hailpad network, calculations were made of the size of each hailstone, whose mass and kinetic energy were taken simply as a function of the diameter of the stone. In this way, an estimate has been made of the total quantity of ice which fell in each hailfall (circa 19,000 tons on average, although a figure ten times this was calculated for one particular hailstorm) and the spatial evolution of the physical variables of the hail, determined from each pad, has also been represented graphically.
In addition, on the premise that all the stones in a hailfall proceed from the same population despite having fallen over different hailpads, the distributions of hailstone sizes has been analyzed, and the characteristic distribution parameters calculated. The information provided by these parameters has been analyzed both for exponential and for gamma distribution, in relation to some specific meteorological variables and indexes of atmospheric stability.