Graupel trajectories and charging: a new numerical approach for cloud electrification studies

MASUELLI, S; M. PULIDO; M. SCAVUZZO AND G. CARANTI

QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY

JOHN WILEY & SONS LTD

Lugar: Reading UK; Año: 1998 vol. 124 p. 1329 - 1341

0035-9009

calculated by a three-dimensional cloud model. Anothcr program calculates the time evolution, inside thesecloud fields, of graupel properties (size, position, charge and others). The electricity enters bolh in the charging ofthe particles through their interactions with other particles and in the motion itself, since in the equation of motionthe electrical force is included. Embryos with 500 pm initial diameter are released at 656 locations uniformlydistributed in the updraught centre at four altitudes. The trajectories of all the particles are followed all the way tothe 0 -C altitude. The graupel is charged by the icc-crystal-graupel non-inductive mechanism.This kind of approach appears to be a powerful tool to study the electric charging of the graupel in greaterdetail, since a very high spatial resolution (about 1 m) is easily achieved. Some preliminary analysis of the chargeson the precipitation particles is carried out and thc rcsults are related to in situ observations. For the sake ofcomparison, trajectories without the electrical interaction are also computed, and it is shown that in some cases thefinal radius with and without the electrical force can differ by a factor of two to three in either dircction dependingon the initial position.