Well if you want the cloud to spread it will depend on what clouds youre using.If you are using particle clouds then you can attach a uniform field to your aircraft , using a volume sphere mode.The uniform field will push the clouds away in the desired direction, will take some experimenting to get the desired speeds at which you want the cloud to move away, this u can achieve either with keyframing the magnitude of the field OR by using expressions.
As for fluids too im guessing that they can be affected by Mayas dynamic engine hence allowing you to use the same method mentioned above.
But again it will take tral and error to get thing moving exactly the way you want them to.