In Callisto, I needed to add some motion to the scene, some visual activity to make the place seem alive! Since it's technically a fairly barren ice moon, with more snow than life, it made sense to add something to make it look windier.
I quickly settled on a cartoonish looking wind swirl, which you can see above! It looks cool, it's easily recognizable, and it's super easy to implement quickly! I didn't even need to write a custom shader for this, as it's accomplished entirely through scrolling the UVs on the material.