Figure 2.

Behavior of a gas, a liquid and an aerosol within a closed volume. An aerosol is a suspension of liquid droplets within a gas. A gas expands homogeneously within a close volume, a liquid does not (assuming a constant temperature). An aerosol has an intermediate behavior. The smaller the droplets, the closer the behavior is to a gas; the larger the droplets, the closer the behavior is to a liquid. Due to gravitational force, every aerosol has a vertical concentration gradient and will sediment over time to the bottom of the container.