Definition:Homogeneous (Physics)/Warning

Definition
Just to specify that a body is made of the same substance throughout is not an adequate definition of homogeneous.

For example, a column of air in the atmosphere is denser at the bottom than at the top.

The fact that it is "all made of air" is one thing, but the air at the bottom can be distinguished from that higher up because the densities are different.

Thus a column of air is not homogeneous.