1Lab. Física de la Atmósfera, Instituto de Medio Ambiente, Universidad de León - Spain
2Laboratoire d'Aérologie, Observatoire Midi-Pyrénées, Université de Toulouse - France
The physical properties of hailstones registered by a hailpad network (size distributions, mass, kinetic energy) are essential data for the establishment of a regional hail climatology. The study of hailstorms by means of a meteorological radar is also interesting, but when compared with the hailpad data the melting process must be taken into account here.
In the province of León (northwest of the Iberian Peninsula) a network of 250 hailpads (one every 4 km2) provided the data to establish the parameters of the hailstone size distribution. In addition to this, a weather C-band radar was used to identify the hailstorm echoes when passing over the hailpad network in order to search a relationship between the intensity of the hailstorm and the hail on the ground. Nevertheless, the melting of the hailstones must be taken into account to find a good relationship between both systems, since melting varies the size of the hailstones and can even make the smallest ones disappear. Consequently, the general hailstone size distribution may change. This paper presents a brief theoretical study of the changes effected on the hailstone size distribution due to the melting process.
Every hailstone that hit a hailpad from the network in León was measured over the period of a whole summer. The estimated size of every hailstone inside the cloud was calculated taking into account the meteorological conditions. Moreover, the theoretical distributions and the estimations were compared. Finally, the dependence of the radar variables on the hailstone size distribution before the melting process was also analyzed.