AbstractCalculations of direct beam radiation are combined with diffuse radiation measurements to produce maps of the global radiation for all slope facets of a forested hill at latitude 45°. Net radiation is derived from the global radiation calculations to give the radiant heat energy available for evapotranspiration and the sensible heating of air and soil on north and south slopes. Measurements of weekly evapotranspiration, the seasonal regimes of soil moisture, snow accumulation and melt, and air and soil temperatures are presented for north-and south-facing slopes.The greatest slope differences in global radiation occur in the fall and winter, whereas in summer, variations due to exposure are minimal. Accumulative evapotranspiration over the growing season shows little difference between north and south slopes although substantial differences were noted before leaf development. Differential snow melt leads to complete snow removal from south slopes which is three weeks in advance of those facing north. As a result, north slope soils have stored 50% more water than their southern counterparts by early spring. Trend surface analysis shows that the spatial distribution of surface soil moisture is correlated with the cubic shape of the hill in early spring and that this pattern persists for at least three months. The greater consumption of available heat for evapotranspiration from north-facing sites results in lower air and soil temperatures than on south-facing ones.