… Hoth … bright, sunlit areas are very white, but the overcast and shadows are more blue and … a triangle of blue sky visible through the smoke and the sky to the left should have some touches of blue. Also … smoke to the far right should have a very gray, almost bluish tone.
Gentle-curve tweaks of Green (weaker at mid and high) and Blue (stronger at mid but weaker at low) with other points anchored (to not throw off the rest) will get this:
