ON THE ANNUAL HEAT BALANCE OF THE NORTHERN HEMISPHERE

Abstract The increased knowledge of atmospheric radiation during the last twenty years has made it desirable to re-compute the heat balance of the northern hemisphere. Insofar as possible the computations are based on observational data and, in particular, no assumption is made regarding the planetary albedo nor the albedo of clouds. The solar radiation reaching the surface is derived largely from the North American pyrheliometric network. These data are extended to the hemisphere on the basis of the differences between the cloud amounts along complete latitude circles and the cloud amounts along the North American segments. Absorption of solar radiation in the atmosphere is computed from the original Smithsonian data. Absorption by clouds is taken into account. The outgoing long-wave radiation is computed on the Elsasser radiation chart, with use of monthly mean data from a large number of individual stations. The planetary albedo is found to be 0.34, with a minimum of 0.28 in the subtropics and a maximu...