This session focuses on new observations of atmospheric phenomena on sub-km, sub-diurnal scales enabled by active optical remote sensing (lidar) methodologies. Contributions describing original research results from ground-based, airborne, and space-based observational vantage points are solicited. In particular, aerosols are important in climate, radiation budget, and cloud formation research. One of the goals of the session is therefore to survey the state-of-the-art of elastic backscatter lidar for determining the vertical and horizontal distribution of clouds and aerosols throughout the atmospheric column. Another topic that benefits greatly from lidar is the elucidation of chemical and physical processes that occur in moderately and heavily polluted environments such as megacities. For this application it is necessary to accurately describe the planetary boundary layer dynamics and depth evolution (a field in which lidar techniques excel). Other topics of interest for this session include: Process studies related to atmospheric composition, pollution, transport, and dynamics, and convective storm development.