Estimates of solar radiation at the earth's surface are given based on a parametrization technique which employs 24 months of satellite-derived cloud cover data (Sadler, 1969) and surface radiation measurements with established calibration traceability to the International Pyrheliometric Seale (1956). The zonal average solar radiation is presented as monthly and annual averages for each 2.5¿ from 30¿N to 30¿S. The global average solar radiation at the earth's surface is determined from the present study together with data from Ashbel (1961) and London and Sasamori (1971) as 0.286 cal/cm2 min. This value and satellite measurements of global albedo suggest that the most likley values for the global solar radiation terms are (in proportion to that intercepted by the earth) 0.29 reflected to space, 0.19 absorbed by the atmosphere, and 0.52 absorbed by the earth's surface. The implications of the present study to the climatic model results of Budyko (1968) and Sellers (1969) are considered.