SURFRAD Total Sky Imagers (TSIs)
G-Rad collects data from Total Sky Imagers located at each SURFRAD site. The TSI consists of a web camera suspended over a convex mirror. The mirror has a black sun-blocking stripe, which rotates during the day to protect the camera's sensitive picture element from bright sunlight. Images of the sky are collected by a local computer, and processed into percent cloud cover data. Daily cloud cover data are available for all sites.