What is density? how is the density of air affected by its temperature?

1. Density is the amount of matter in a given volume or area. Density is also described as a measure of the compactness of matter. It is determined by dividing the amount of mass of a substance by its volume. D=m/v

2. As air is heated its density decreases because its mass remains constant but its volume increases. As air is cooled, its density increases because its mass remains constant but its volume decreases