Our research focuses on quantifying the evolution of the droplet size distribution (DSD) in-cloud, by exploring various mechanisms that may be responsible for the initiation of precipitation. Two key questions are being addressed. Firstly, can the sub-cloud aerosol size distribution, without the mechanisms of entrainment and mixing, and turbulence, account for the production of the largest drops observed at various altitudes in-cloud? Secondly, what effect does entrainment and mixing (varying from homogeneous to inhomogeneous) have on both the breadth of the DSD, and the concentration of the largest drops within different regions of a cloud? In order to examine the influence of the sub-cloud aerosol size distribution on droplet spectral broadening, comparisons will be made between observed DSDs and those produced by an adiabatic Lagrangian parcel model, at various altitudes above cloud-base. Furthermore, the impact of entrainment and mixing will be investigated by comparing observations with output from a modified version of this model run along trajectories produced by a 3D cloud model. The talk will highlight significant findings from each of these studies.