Fluctuations of the cloud top (CT) were studied with an airborne lidar, and the spatial spectra of the CT were obtained. For the stratus they follow, on the whole, the "-5/3" power law. In some cases, the intensity of fluctuations of the atmospheric inhomogeneities with the scales less than 100 m decreases much faster. Horizontal dimensions of the CT inhomogeneities were found to obey the power-law distribution, while their vertical dimensions obey the exponential-law one. The empirical relation between the mean horizontal and vertical dimensions of the CT inhomogeneities was obtained.