Two-dimensional Lagrangian model of a rising thermal: application for a liquid water content spatial variability of a warm cumulus cloud

A two-dimensional numerical model is used to simulate a liquid water content field (LWC) within an isolated thermal with a spatial resolution of 20 m. The model is based on the shallow Boussinesq anelastic convection equations written in terms of x-z vorticity component, equivalent-potential temperature and the total moisture content. They are integrated numerically using a Lagrangian frame. The model flow and LWC fields reproducing the early stage of a bubble-like thermal development are presented. As shown, a LWC spatial variation within a thermal can be caused by a different origin level of air parcels without considering explicit mixing along the thermal boundary. Two principal patterns in the cloud LWC field are revealed, which are controlled by the form of equivalent-potential temperature vertical profile in the environment.