The largest network of surface cameras ever established in the tropics for studies of cloud cover was deployed during the. Global Atmospheric Research Programe's Atlantic Tropical Experiment (GATE) in 1974. Analysis was made of 2572 hourly whole-sky photographs taken aboard four U.S. ships during the daytime hours of nearly every day covering the three phases of GATE. The cloud-cover analyses were made on a grid divided into 100 squares covering most of the overhead sky, much as previously made for Barbados and adjacent Atlantic Ocean cloudiness. Analyzed cloud types include low, middle, high, two kinds of total, and two kinds of combined upper cloudiness. Rainfall duration was obtained from drops impinging an the glass dome covering the whole-sky lens. Average total cloudiness was between 70 and 85% for different ships and individual phases of GATE. From 22 to 56% were low clouds, and the rest were upper clouds. Large standard deviations of means are attributable mainly to frequent values near 0... Abstract The largest network of surface cameras ever established in the tropics for studies of cloud cover was deployed during the. Global Atmospheric Research Programe's Atlantic Tropical Experiment (GATE) in 1974. Analysis was made of 2572 hourly whole-sky photographs taken aboard four U.S. ships during the daytime hours of nearly every day covering the three phases of GATE. The cloud-cover analyses were made on a grid divided into 100 squares covering most of the overhead sky, much as previously made for Barbados and adjacent Atlantic Ocean cloudiness. Analyzed cloud types include low, middle, high, two kinds of total, and two kinds of combined upper cloudiness. Rainfall duration was obtained from drops impinging an the glass dome covering the whole-sky lens. Average total cloudiness was between 70 and 85% for different ships and individual phases of GATE. From 22 to 56% were low clouds, and the rest were upper clouds. Large standard deviations of means are attributable mainly to frequent values near 0...