Flux measurements from the 415 nm band of the multifilter rotating shadowband radiometer and liquid water path from the microwave radiometer were used to derive effective radii in warm boundary layer clouds at the U.S. Department of Energy Atmospheric Measurement Program Southern Great Plains site. Surface fluxes computed using the effective radii retrieved using 415 nm measurements showed no bias when compared with observed broadband fluxes. It is therefore inferred that there is no excess absorption at solar and near-infrared wavelengths in the presence of warm boundary layer clouds.