Heavy Smoke is filling the frame, smoke machine, flowing, from left to right, filling all the composition (frame), fading (fade) in and out, washed out, blurred or sharp patterns and shapes formed by smoke. Quality of a pure natural super fluent liquid Smoke not a 3D visualization. Perfect to create mystique dark atmosphere, scary effect, weather conditions, happening, add unique look to your footage adding this smoke as foreground or as background. Could be a part of a transition, opener or placeholder.
It doesn’t have transparency, as it holds more details and more room for post workflow when on black. Transparency could be achieved in one click by setting blending mode (Layer Mode) to “Add”. Duplicate the layer to get brighter smoke.