New mathematical models of stochastically nonuniform cloud fields are considered taking into account a random geometry of individual clouds. These models are constructed on the basis of sum of independent random Gaussian fields with decreasing variances and correlation lengths that is essentially close to the so–called cascade processes, which are used in simulations of the fractal clouds. The cloud fields which are simulated on the basis of Poisson and sum of normal cloud fields are most close to actual cloud fields. Within the context of the method of numerical simulation of cloud and radiation fields the algorithms of the Monte Carlo method for calculation of linear functionals of mean intensity have been developed and the effect of the random geometry of individual clouds on the mean fluxes of visible solar radiation have been evaluated.
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