One approach is to use a BPM expression to control the Density of the cloud, for example:
(1 bpm: !BPM dutyCycle: 0.05) * !Density
Then set CyclesPerGrain to something in the range of 4 to 6 or so.
There's an example in the Sound Library called CloudCluster that uses a Script to make 8 of them (you can search for it by name in the Sound Browser Search).