I have only one very small unable

the Principle is clear, it is necessary to work out, apparently.
But
the summer heat, the moon is not visible, cloudy, could be rain, could not be, declared a storm warning is close and there is nothing similar.
I really like from the cartoon Smeshariki: Meteorology is an exact science, the probability of 50/50, if you were told it would rain, then it is either definitely will or definitely will not be.
With the clouds I have that same cloud, not collected, yet Sunny.