There doesn’t seem to be a trick here. Most pictures are either long-exposures of moving things (clouds or water), or hazy shots. In both cases, they all have a milky background to begin with.
Then, it’s only a matter of driving your contrast curve. If you look carefully, none of his pictures have true white (easy to compare against the white background), which ensures details even in the brighter areas. And most of them don’t have true black either (you read details even in dark blobs). But all of them have the utmost attention given to the midtones (while most amateur photographers spend too much time on the extreme luminance values and forget the “meat” in the middle).
The guy is basically a master of the dynamic range with a keen eye for graphic scenes with a dreamy soft spot. All you have to do is to become a master too… I mean, I don’t see any post-processing tricks I could dissect for you here. It looks a lot like any basic levels/curves stuff, just done with taste and skills.