为了研究不同物理厚度和不同波段下云的红外辐射特性，提出了基于光学厚度的云红外辐射计算方法。综合考虑云的红外辐射的各个因素，建立了较为完善的云的红外辐射模型，引入光学厚度经验计算公式，并根据光学厚度针对中波和长波红外分别计算了云的发射率、反射率和透过率，进而得到云的红外辐射亮度分布。利用该计算方法，计算了中波和长波红外云的辐射亮度数值，计算结果表明：随着光学厚度增大，云的发射率和反射率增大，探测器接收到的云红外辐射增强。比较发现，该计算结果与实测数据有较好的一致性，该计算模型可以为云背景的红外特性分析、探测及仿真提供参考数据。

To study the infrared characteristics of clouds with different thicknesses in different wavebands, a method for calculating infrared radiation of cloud based on optical depth is proposed. The infrared model of cloud was established after studing each infrared radiative component. According to the relation of infrared characteristics to waveband and thickness, the emissivity, reflectivity and transmissivity were computed respectively in middle infrared and long infrared wavelength, and the radiance of cloud was computed accordingly. Result shows that the radiation of cloud is a funtion of optical depth, and the actual measurements and the data from the model are consistent. It is proved that infrared radiation calculation of cloud based on optical depth can be used as the data source in infrared characteristic detection, analysis and simulation for the cloud background.