This is an image from Rocky Mtn NP back in August 2011. Started in LR and exported a color version which I then opened in Nik Silver Efex Pro. I selected a high structure preset and applied a film type, in this case Agfa APX Pro 100. Thought the grain worked well with the clouds - my photographic roots are from the film days and developing Tri-X 400 film and prints at home, so I like the grainy look. I also applied a red filter to get more dynamic range in the sky. However, the foreground mountains are somewhat underexposed. I used a blue filter which lightened up the receding mountains adding some nice depth. I’ve found that blue and cyan filters in b&w conversions behave somewhat like a haze/dehaze tool. Can also make use of this effect in color images by using blending modes with b&w layers. My final step was to load these two Silver Efex images into Photo FX Lab. Yes, I still occasionally use that very old Topaz program. Used a simple mask to blend the 2 layers. Then tweaked it a bit with some dynamics and shadow adjustments.
Thanks for looking and best regards.