Adding atmospheric perspective to a scene using Cycles and HDRI I spent a few hours trying to find a solution... I'm looking to get the effect of atmospheric perspective in my scene to help me understand lighting more. I have an HDRI and I'm using cycles and I've tried the following....

Add a volume scatter to the "Volume" tab in World properties. This breaks my HDRI and it just renders black even with a density value of 0.000015

I tried creating a large sphere encompassing my whole scene and adding a Volume Scatter shader to it. Scene renders, but there is no sun lighting from the HDRI, just dark blue ambient lighting it seems. I tried adjusting the density value to around 0.00001 and I can either get the scene to render normally with no atmospherics or as a dark scene described earlier.

Is adding atmospheric perspective in Blender 2.79 possible?
I think you want atmospheric lighting if I understand correctly. There is definitely atmospheric support for cycles. However, sun lamps do not work. Use a Point lamp, Spot lamp, or Area lamp. Also, make sure the strength is rather high. You should use Volume Scatter. If you want a mist effect, where objects fade away the further they get, you can try this tutorial. This will allow for less noisy and faster renders.