Dr. Tomasko will continue a project to study the properties of particles which make up a haze in the atmospheres of Jupiter and Saturn. Most of the necessary ground-based observations are in hand, but reduction and analysis of the data remain. Visible images of Jupiter and Saturn reveal the presence of bright and dark cloud features over the disks of these planets. Such solid cloud particles can play important roles in the chemistry, heat balance, and dynamics of planetary atmospheres. It is now known that a relatively thin haze of small particles is formed in the stratospheres of both Jupiter and Saturn by photochemical reactions, possibly augmented by meteoritic infall. These particles fall to tropospheric levels where they can act as nuclei for the condensation of several atmospheric gases, including ammonia. Despite the importance of these particles in planetary processes, the complex nature of their interaction has made it difficult to use remote sensing observations to uniquely determine their properties. Dr. Tomasko's project is aimed at obtaining a coordinated set of ground-based observations of Jupiter and Saturn which will substantially enhance our understanding of these haze particles.