In this exercise I use trapcode particle to create smoke effect. In trapcode, I turn down the particle velocity all the way down to 0 so that the particle will not flaying anywhere, and only effect by winds. I also turn up the turbulence to create distortion, making the effect more smoke like.
the opacity of the particle is about 3%, and I have the opacity overtime from 0 to 100 then back to 0. This will make the smoke slowly fade over time.