This topical issue of the Journal of Pure and Applied Geophysics focuses on research related to dew and various types of fog occurring around the globe which was presented on July 25-30, 2010, at the 5th International Conference on Fog, Fog Collection, and Dew in Münster, Germany. The areas of knowledge in this field include surface in-situ and remote sensing observations of fog, dew, fog collection, applications of the various fog models (such as 1D, 2D, and 3D fog and forecasting models), microphysical parameterizations, and climatology. This volume gives a very good review of the existing knowledge and highlights the remaining difficulties in predicting and measuring fog at various scales of time and space. It also represents an important step in the direction of addressing new scientific challenges in fog and dew related research, teaching, and operational applications. Students as well as researchers, who are interested either in fog, in association with cloud physics, physical meteorology, aviation meteorology, climatology, weather forecasting and nowcasting, or in other adjacent disciplines like hydrometeorology, environment, and agriculture, will benefit from consulting and reading this topical issue. This publication was significantly supported by the Canadian National Search And Rescue (SAR) Secretariat by funding the Fog Remote Sensing and Modeling (FRAM) Project led by Dr. Ismail Gultepe since 2005.