We present here estimates of return signals of an orbiting lidar intended for sounding clouds. The estimates are obtained using Monte Carlo method. The calculations are performed for λ = 0.532 mm. Here we analyze the clouds of a homogeneous optical structure. The signal structure is shown to vary within a cloud layer of ΔH = 100 m depending on optical and geometrical conditions of the experiment. As follows from the analysis of the results extinction coefficient is the main parameter that determines the lidar return structure. Variations of the scattering properties of a cloud do influence the return signal formation only insignificantly.