The problem of the backscattered laser radiation field formation is solved based on the theory of optical radiation transfer in broken cloudiness as a scattering medium with random geometry. The dependence of the energy characteristics of a lidar return averaged over the ensemble of cloud-field realizations on the type of clouds (cumulus and stratus), cloud fraction, optogeometrical parameters of a cloud field, lidar's geometric parameters, and the distance to a cloudy layer. It has been shown that over long periods the multiple light scattering between the cumulus clouds is the dominating contribution to the lidar signal power.