You have multiple sources of noise in your animation. A lot of it is what looks like low antialiasing in your plant models on the ground (noisy ground). You also have some popping in the cloud shapes which I would guess is due either to using Acceleration Cache in clouds (you can try "Conservative" acceleration if you are set on anything higher, it might work and still be faster than None), or may be due to Accelerate Empty Space in cloud Optimization tab.
- Oshyan