Relative Size : as an object is farther away, its retinal image size shrinks.
Relative Height : Relative to the horizon and mostly misdefined. Simple: The closer an object is to the horizon, the farther away it appears. Complex: If the object is on the ground, the higher in the image, the farther away it appears; if the object is in the sky, the lower in the image, the farther away it appears.
Texture Gradient : if a pattern gets consistently smaller in one direct, then the plane recedes in that direction. If the pattern does not get smaller in any direct, the pattern is vertical opposite your direction of view.
Linear Perspective : parallel lines converge as they recede.
Areal Perspective : just as the sky is blue, distant objects are both bluish and somewhat hazy. Thus, the Blue Ridge/Smokey Mountains.
Shadow : shadow reveals depth and texture by the pattern of what falls in shadow and in the light.
