Thickness of normal shock zone (e.g. in nozzle)

[Swamp Thing]

Under certain conditions, a supersonic flow in a nozzle will result in a "normal shock", an abrupt change in pressure and velocity. In the videos I've looked at, they draw the P and v graphs with a vertical step at that point.

But in practice, I assume there will be a non-zero transition zone with a finite slope in the relevant parameters? And if so, what would determine the thickness of the shock zone, i.e. the slope of the transitions?

 

[jack action]

In a shock wave the properties of the fluid (density, pressure, temperature, flow velocity, Mach number) change almost instantaneously. Measurements of the thickness of shock waves in air have resulted in values around 200 nm (about 10−5 in), which is on the same order of magnitude as the mean free path of gas molecules.