Okay, so I found the cloud particles in the Shooter Demo. Just search for “Cloud” in the root Content folder and then filter to particle. You’ll find P_clouds_1, P_clouds_2, 2_brighter, and a bunch of highrise clouds. They’re the best example of particle clouds I’ve seen. Of course, they’re not volumetric so they look weird when you’re inside them, and they’re huge so they’re meant to be placed 100,000 units up in the Z axis at least. Also, you can adjust the custom time dilation to make them move faster. I set the highrise ones to 5 and it looks pretty good.
To clarify, you don’t want to use Particle clouds to fake volumetrics (ie clouds you move through). Particle clouds are for a cheap alternative to volumetric clouds that gives you a feeling of depth because they can obscure tops of buildings or hang around mountains. If you want to fly through clouds and not get the weird rotational effects, that’s what the volumetric system is for which leads to the fog…
As for the Fog, if you make your own custom volumetric particle system following this tutorial; UE4 Tutorial: Local Volumetric Fog - YouTube
You can then use the method outlined in the previous post which is to use a blocking volume and set its Collision Preset to match the Object Type of your Custom Fog Particle’s collision setting (EG: World Static).