Hello everybody, just got UE4 and I am loving it thus far. I am having an issue with my particle emitter and I was hoping to get some help. I apologize if this isn’t the appropriate forum for this. Please forgive my ignorance with the engine as I am still new to game engines and game creation in general. Ok, on to the issue. So, I created a particle emitter for a falling snow effect. The effect looks great but my emitter seems to function for about 10 seconds, pause, then restart. Is there anyway that I can get the emitter to just emit constantly? I’ve tried playing around with the various settings but haven’t had any luck. Also, is it possible, and if so how, to get my emitter to emit over a large area? My scene in general is pretty small but my emitter seems to only emit in a very small radius. Thanks for any assistance.
Quick Solution to your second question:
You can attach your particle system to the player using Blueprint therefore whenever player walks he will see like there’s snowing.It’s pretty cool illusion!
To make it constant,I think you have to set your emitter’s Lifetime to 0.0.
Hello Arkenthera and thanks for the reply. I did try setting the lifetime to 0.0 but I still had the issue. I finally solved my dilemma with the delay in the emitter by setting it to run as GPU particles. I had considered attaching the emitter to the player, that is probably the route I will take. I would imagine the overall performance will be better with the emitter attached to the player. I have discovered a new issue however, my snowflakes seem to be leaving tails behind them, reminds me of a comet or something, pretty odd.
While this is possible, it isn’t the best way to do it. I’ve seen a lot of games that attempted to show rain in a similar way, but as soon as a player walks inside, the particle turns off (ohh clever), but then when you look outside, it’s suddenly not raining any more. If you’re running towards an outside area, the rain suddenly spits back into life. The best way to do these types of effects is to literally spread them out over the level, but rely on LOD’s to turn them off over a certain distance. It’s more expensive of course, but it’s the only real way to do it properly, just like the only real way to do smoke properly is layer lots of translucency.
As for spawning over an area, right click your module and choose location -> Initial location. You can then set up a much larger area for the particles to spawn in. Now that the effects demo level is on marketplace, look at how they did it 
There are some more advanced techniques in there, but it should give you a general idea.
As for the looping issue, set you’re particle emitter duration to 0. Just make sure your particles have a lifespan or you’ll end up filling the level with them :). Even with a long duration, the cascade preview will briefly have a pause between the emitter starting and stopping.
Thanks everyone for the responses. I have another issue now. If I turn GPU particles on my snow flakes seem to get weird comet like tails behind them, the problem is without the GPU particles I seem to get that delay I mentioned previously. Also, without GPU particles, the number of flakes I can render at any time seems capped at 1000. Does anyone have any solutions for these issues or perhaps suggestions on work arounds?
Update: I managed to get more flakes falling by adding multiple emitters and it seems the comet tail issue is not related to GPU particles. It seems to be caused by having a large number of flakes falling. Anyone know how to resolve this issue?
Use Max Draw Count When true, the emitter will never draw more than MaxDrawCount particles. All particles will still be updated when ticking.
Max Draw Count The number of particles to limit rendering to.
Located in the required module, Also there is the bounding box controling from where to where distance-wise from emitter center particles will be drawn, And last but not least my input to your issue is, I would find a way to have those particles follow each player camera and follow it plus i would add collision and death on impact thus particles wont enter closed areas. I would also be trying to problems solve any height issues from affecting the player if in a building or under stairs.
PS: I suggest you start here and work your way. Cascade Particle Systems | Unreal Engine Documentation