I was looking some awesome images with bridges and some volumetric lights, mist and then I thought…
Maybe if the mist has some shapes would be great… Let’s try adding a Musgrave to the volumetrics of the World…
At first it didn’t because even if the color is black the volume would appear as black and not “no volume” then It hit me I have to mix 2 volumetrics! One that has volume and the other that doesn’t!
And it worked !
Edit:
And then you can even animate it the Mapping node (Location X) to make it move 