The albedo of a pine forest

The albedo of a pine forest was measured for a total of 243 hours during the summer of 1970 by pairs of Kipp solarimeters whose output was recorded by a computer controlled data acquisition system. It was found that the mean albedo was 9.1 per cent. On cloudless days there was a pronounced dependence of albedo on solar zenith angle; however, on cloudy days there was little variation. The effect on the albedo of the wetness of the canopy was less than one per cent except at large solar zenith angles. The mean albedos for June and December were calculated and found to be 8.9 and 11.7 per cent respectively.