Exploring Atmospheric Perspective in the famous 'Three Sisters'.
Let's take a vertical section of this scene in order to more clearly see what nature does to colour.
Notice how the olive green becomes a blue green in the distance.
Same trees, same day, different colour from our viewpoint.
Using Tone to create planes in a Landscape
Three tones are enough to create planes in a landscape.
In this student painting we can clearly discern: