S. Masuelli et al., CONVECTIVE ELECTRIFICATION OF CLOUDS - A NUMERICAL STUDY, JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 102(D10), 1997, pp. 11049-11059
Although the convective process of cloud electrification has been prop
osed long ago, there is a lack of numerical simulations in the literat
ure that would put this mechanism to the test. A numerical model devel
oped with the purpose of evaluating the electrification caused by the
convective mechanism alone is presented. More precisely, in the model
only the interaction between free ions and cloud and precipitation par
ticles separates charge. The ability of this mechanism to reproduce th
e most important features of cloud electrification is discussed. The s
tudy is carried out on a slab symmetric domain of 16 km per side. The
microphysics is represented by a bulk parameterization including four
categories: cloud ice, cloud water: hail and rain. The model also incl
udes aerosols and small ions, and it takes into account the difference
in mobilities between positive and negative small ions. The influence
of variables such as the number of particles, number of aerosols and
ion pair formation rate is tested. A dipolar structure bounded by the
cloud is obtained. The magnitude of electric field is too modest to pr
oduce any lightning after 10 min of simulation.