The first two sections cover nucleation and growth of water drops and ice particles, including evaporation and breakup processes. Further sections address scavenging, motions and interactions of falling particles, chemistry, electrification, and instrumentation. We have tried to establish some perspective for these studies by connecting them with recognized problem areas in atmospheric science. Laboratory studies are usually linked with observational field programs or theoretical work. The distinct advantages of the laboratory approach are the high degree of measurement precision, repeatability, and control over experimental conditions. Its disadvantages stem from limitations in scaling the results up to the size, time, and complexity of the real atmosphere. -from Authors