If you don't need to use particles, you could try reading this thread:
https://forum.simplymaya.com/showthre...ghlight=clouds
Otherwise, here's a way to do it with particles:
https://3dtreat.com/pages/tutorials/C...age/index.html
You could also read up on Fluids if you're using 4.5 or above. Unfortunately, it seems that one of the better resources for natural phenomenon type of effects, including clouds with particles, (mentioned in the first link's threads) is currently out of commission.
"Terminat Bora Diem, Terminal Auctor opus."