Andrew Tischler is an artist based in New Zealand who specializes in oil paintings of a variety of different subjects and his Youtube channel is loaded with great videos and tips that not only apply to oils, but other mediums as well. In this video Andrew talks about the effects of atmospheric haze and how that impacts the illusion of depth. If you've ever done any distance landscape photography you will have seen the haze impact because, despite the close up appearance, our atmosphere is not completely transparent.
Now, photographers actually try to remove some of that haze (Photoshop and Lightroom have de-hazing tools built in), but when it comes to painting, the haze actually plays a role and allows us to create depth and avoid having the image look flat and fake. So, with that: