Density of air

The density of air, ρ (Greek: rho) (air density), is the mass per unit volume of Earth's atmosphere. Air density, like air pressure, decreases with increasing altitude. It also changes with variation in temperature or humidity. At sea level and at 15 °C air has a density of approximately 1.225 kg/m³ (1225.0 g/m³, 0.0023769 slug/ft³, 0.0765 lbm/ft³) according to ISA (International Standard Atmosphere).

The air density is a property used in many branches of science as aeronautics;gravimetric analysis; the air-conditioning industry; atmospheric research and meteorology; the agricultural engineering in their modeling and tracking of Soil-Vegetation-Atmosphere-Transfer (SVAT) models; and the engineering community that deals with compressed air from industry utility, heating, dry and cooling process in industry like a cooling towers, vacuum and deep vacuum processes, high pressure processes, the gas and light oil combustion processes that power our turbine-powered airplanes, gas turbine-powered generators and heating furnaces, and air conditioning from deep mines to space capsules.