The U.S. meteorological satellite program has matured considerably since its beginning on April 1, 1960. The program now has a regular, routine, observational part but also continues a vigorous expansion into new types of measurement [Johnson, 1970; Tepper, 1967].
Operationally, the world is observed routinely every day; digitized mosaics of the world's cloud cover are obtained regularly by means of AVCS (Advanced Vidicon Camera System) television cameras and tape storage [Johnson, 1969]. In addition, about 500 stations in over 50 countries receive cloud pictures daily of large areas surrounding each station through APT (Automatic Picture Transmission). Also, infrared radiation data in the form of pictures are beginning to be received with operational regularity from ITOS 1 (improved Tiros) [Albert, 1968].