INVESTIGADORES
AVILA Eldo Edgardo
artículos
Título:
A laboratory study of the influence of the water vapour and mixing on the charge transfer process during collisions between ice crystals and graupel
Autor/es:
C. SAUNDERS; S.L. PECK; G. G. AGUIRRE VARELA; E. AVILA; N. CASTELLANO
Revista:
ATMOSPHERIC RESEARCH
Editorial:
ELSEVIER
Referencias:
Año: 2001 vol. 58 p. 187 - 203
ISSN:
0169-8095
Resumen:
Laboratory experiments, in which vapour grown ice crystals interact with riming graupel
targets, simulate charging processes in thunderstorms. The introduction of cooled, moist, laboratory
air into a supercooled droplet and ice crystal cloud enhances charge transfer and, when the
air-stream is directed at the riming target, can reverse its charge sign. The suggestion is that the
extra water vapour introduced increases the supersaturation and influences particle diffusional
growth. The results have been considered in terms of the Relative Growth Rate Hypothesis, which
states that the interacting ice surface growing fastest by vapour diffusion charges positively. A
corollary to this was noted, when dry air is introduced into a cloud of ice crystals so that both the
crystals and target surface sublimate, the ice surface that sublimates fastest charges negatively.
The experiments are relevant to considerations of the reasons why earlier sets of charge
transfer results give different liquid water and temperature boundaries between positive and
negative graupel charge sign. The differences appear to be connected to the techniques used, in
particular, to the mixing of separate droplet and ice crystal clouds before riming, which can lead to
positive rimer charging in conditions of low-rime accretion rate, as observed in the present study.
Further work is needed to resolve questions concerning the most naturally representative manner
of performing these laboratory simulations.