I'm try to set up a smoky background with particlar and have no luck,
I've pick smokelet and move the position of the emitter from left to right so the smoke will fill the whole screen.
Everything looks fine, except whenever a new particle are generate it doesn't fade in or out,
it just pops up, Ihave already adjusted the opacity over life so to curve up and back down from brith to death,
but it doesn''t help,what cloud be the problem?
Most likely your particle lifespans are simply too short so the fade phases are only a few frames. If it's an option, you may want to animate the particle size as well. In addition to that, you should try to use more particles, but with lower opacity settings. This will minimize the effect.