Capturing droplets from a stream with a fibrous material is a well-known and well-used process, from face masks or coalescence filters to fog collection. Using a combination of lab model experiments and measurements on a large scale in situ fog collector placed on a meteorological station, we investigate the mechanisms of droplet capture as well as the aerodynamics effects at play for different net geometries, from high porosity fog collectors to low porosity filters. In particular, both in the lab and in situ, we study the drag applied on the net and the flow deviations that may occur around the net; in addition, we characterize the capillary growth of droplets on the fibers, and the effect of this liquid distribution on the capture efficiency. Using these results, we develop a predictive theoretical model that can be used to design a robust, efficient mist collector, that we validate with lab experiments. We propose a structural design to ensure a maximized capture efficiency, and we further use this model to link the in-situ measurements of collection efficiency and drag forces with the characteristic of the fog obtained from meteorological measurements.