This is a cylinder, displaced on a coarse scale and textured on a fine scale with animated psrdnoise to mimic a plume of turbulent smoke. Or, rather, turbulent steam, because it dissolves into nothing. The likeness is not great, our cheap trick to modulate the opacity stops working when the cylinder is viewed along its axis, and the code for this shader is a messy jumble of haphazard expressions, but we wanted to include at least one example with a more complex animation aiming for better realism.
Creating animated realistic procedural shaders that look good takes time, experience and artistic talent, and we lack at least some of those. We have to leave the creative use of our noise function to others.