The objective of this study is to determine the mechanism responsible for the formation and perpetuation of large and conspicuous rifts and gradients often visible in satellite observations of otherwise uniform stratus and stratocumulus cloud decks. A fully instrumented Twin Otter aircraft operated by the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) will measure cloud and aerosol properties in and around the cloud-free regions. The data will be analyzed with the purpose of producing a physical model of the marine boundary layer that explains the formation and longevity of the rifts. Flights will be conducted from Monterey, California. Results of the study will be valuable for modeling aerosol and warm cloud processes, understanding the radiative properties of maritime clouds, and for interpretation of satellite data. The project is supported as a collaboration between Dr. Albrecht and Drs. Haflidi Jonsson and Philip Durkee at the Naval Postgraduate School.