Changes in the diffuse and direct solar radiative fluxes observed at the surface can serve as a direct indication of how efficiently a stratospheric aerosol layer removes solar energy from the troposphere and thereby causes tropospheric cooling. Observed changes after the eruption of Agung in 1963 are compared with estimates derived from published results of theoretical calculations for the impact of stratospheric aerosols on the earth's energy budget. The comparison reveals that the aerosol layer that formed after Agung could have caused two to three times the tropospheric cooling obtained with the theoretical calculations. The discrepancy, is, however, mitigated by the large uncertainties associated with the observations. Because of the large uncertainties, the theoretical results cannot be regarded as unrealistic. To reduce the observational uncertainties, is is recommended that (1) the change in diffuse to change in direct flux ratio be derived from observations of the diffuse to direct ratio obtained with a single instrument, so that errors associated with photometric calibration are eliminated, (2) auxiliary observations be made so that changes caused by the stratospheric aerosol layer may be isolated from other changes in the atmosphere, and (3) observations be made at sites where background changes are minimal.