Five different cloud models are compared over a broad frequency range. They are the model of Gunn and East (1954), the model of Liebe et al. (1989), Staelin's (1966) model, Slobin's (1982) model, and the model of Altshuler and Marr (1989). A short tutorial review of the theoretical basis and limitations of each cloud model is included. It is shown that the models all tend to agree at frequencies below 40 GHz, and for light to medium cloud conditions; however, above 10 GHz and for heavy to very heavy clouds, the models diverge.