I just watched this great tutorial over at digital tutors on creating atmospheric depth in images. The tutorial is centered around digital paintings, but the same information and ideas apply very well to modern photography.
I’ve talked before about using reduced contrast to control the viewer’s eye in an image, and to make things look like they are further away, but this tutorial is one step further. It explores adding color to evoke realistic Rayleigh scattering effects and goes through different types of atmospheric elements (fog, mist, sunsets…) and what elements are necessary to convincingly incorporate them into your image.
Once again, this is an example of learning something that is somewhat outside of the realm of traditional photography which can be used to improve your work and make your images that much better.