sin(x + sum 1/f( |noise| ))

That licking flame effect, with cusps at all scales, pretty wll describes the visual appearance of all sorts of turbulent flow. The image to the left was created by taking the turbulence texture from the previous example, and then using it, not to modify color, but to do a phase shift in a simple stripe pattern.

The stripe pattern itself is created with a sine function of the x coordinate of surface location:

sin( x + |noise(p)| + ½ |noise(2p)| + ...)

Perturbing the phase of its domain produces a ripple-distortion, similar to the spatial distortion you see when you look through shower glass. On top of this you can also add an inner luminance, as I did back in 1984 with the marble vase shown on the first slide of this talk, to simulate the lovely opalescent translucency found in some kinds of marble.