提出地对地链路的云散射模型，用于分析不同类型云对给定波长信号光的信道传输特性。通过模型仿真，定量分析不同通信几何结构条件下，三种云的路径损耗预测，分析了发送、接收仰角、发送光束束散角等因素对路径损耗的影响。结果表明，当接收视场角固定时，最佳通信距离随着发送、接收仰角的增大而减小；当发送光束束散角很小(1°以下)时，需要调整发送仰角使得信号光源在云层下界形成的光斑位于检测器垂直上方，以达到接收能量的最大值；当发送光束束散角较大时，应调整发送、接收仰角使一次有效散射体积最大，使得接收能量最大。通过实验测量云散射链路的路径损耗，验证了结论的正确性。结论与波长相关，选用620 nm和808 nm两种波长激光二极管作为实验及仿真的光源。

The cloud-channel transmission characteristics of given wavelength signal are analyzed by setting up a new ground-to-ground cloud-scattering model. By simulation, the predicted path loss of three typical clouds under given transmission configurations are expatiated theoretically and quantitatively. Furthermore, the effects of the path loss caused by elevation angles and transmitting beam width divergence are analyzed independently. The results show that the best communication range decreases when the elevation angles increase on the condition that field of view is fixed. When small transmitting beam width divergence is considered(less than 1°), the transmitting elevation angle must be adjusted so as to the facula on the bottom of cloud produced by the transmitting source light locating on the top of the receiver, but when transmitting beam width divergence is large relatively, elevation angles should be adjusted in order to make the first effective scattering volume maximal. The field cloud-scattering path losses on the communication range of 11.7 km under different receiving elevation angles were obtained by experiments carried in Nanjing, and the above analysis was validated by data. The conclusions obtained in this paper are wavelength-relevant, laser diode with 808 nm and 620 nm are chosen as the transmitting source light.