In one tutorial that uses the Gas Disturb node inside the Pyro Solver to create disturbance on the smoke, the tutor uses a Control Field: speed to affect disturbance less in the areas of slow velocities. However, in addition, in the Bindings tab (see image linked) he sets the Threshold Field to temperature, rather than the default density.

How exactly does this Threshold Field operate? I believe it somehow relies to the Settings tab - Threshold Range, but I don't follow the relationship. Other tutors keep it as density.

https://freeimage.host/i/C0hSNUb [freeimage.host]



Also, when I check the Visuaization tab-Visualize Energy I don't see any visualisation in the viewport, am I missing a step?

It just acts as another multiplier. By default Gas Disturb applies its effect at the edges of density field (0 multiplier at 0.05, 1 multiplier at 0 density). Setting the threshold to temperature would allow you to apply more (or less depending on the range) disturbance in cold areas of your sim.

Do you mean that the Settings tab-Threshold Range acts as a mask to only allow disturbance in that range, and that the Strength of disturbance is then multiplied by the temperature value in the range so that lower density areas in that range get more of the disturbance affect?