Microfísica explícita para um modelo de nuvem quente convectiva

Abstract

A one and a half dimensional anelastic numerical model of a warm convective cloud with explicit microphysical processes has been developed from Lobato (1994). The model is based on the idea of Asai and Kasahara (1967). Two distribution functions are considered in the model - one for cloud condensation nuclei (19 categories from 0.0076 to 7.6 micra) and another for cloud droplets and raindrops ( 50 categories on a logarithmic scale from 1 to 5000 micra). The prognostic kinetic equations for these distribution functions enable the calculation of drop spectra starting from activation and culminating on rain formation. All the important microphysical processes of warm rain are included in this study: nucleation, condensation / evaporation, colision, coalescence, breakup and sedimentation. Two methods are used to calculate the saturation ratio in the clouds simulated. One of them solve the saturation development equation, the other method doesn't use any equation. Both of them provide accurate predictions for the saturation ratio (values of supersaturation under 5%). We used two simulations based on local cloud conditions to show that there are close similarities between the natural and simulated clouds.