The characteristics that are used to describe air are:
Density
Mass
Pressure.
EXPLANATION:
The density of air differs from one place to another so density characterizes the characteristics of air on that place.
Similarly, pressure and mass also determines the characteristics of air. In normal temperature and pressure the air has the pressure of 1atm and density of [tex]\bold{1.204 \frac{k g}{m^{3}}}[/tex]
In this way air is characterized by the density, pressure and mass.