Some observations of the optical properties of clouds. I: Stratocumulus

Aircraft measurements of broad‐band solar irradiances together with radiance measurements in the 1‐2 to 2‐1 μm region are presented for a stratocumulus sheet. Measurements of the solar albedo and cloud physics parameters indicate that the cloud was very uniform and optically thick. Broad‐band observations of albedo agreed well with calculations but observed absorption was about double the model values. Narrow‐band observations of vertical reflectance at three wavelengths suggested a marked increase in effective cloud droplet radius along the cloud, which was not observed. Some evidence that the discrepancy might be due to cloud top unevenness is presented.