KnowraAir densityAir densityAir density is the mass of air per unit volume. It varies with pressure, temperature, humidity, and altitude.BriefConnectIdeal gas law: An equation relating a gas’s pressure, volume, temperature, and amount of substance. It predicts dry-air density from pressure and temperature when air behaves approximately as an ideal gas.Aerodynamic lift: The force perpendicular to a moving fluid’s flow that acts on a body within it. At a given speed and wing shape, lower air density reduces the lift available to an aircraft.Mass: A measure of the amount of matter in an object or physical system. Air density uses mass as its numerator, so its value depends on which air constituents are counted.Buoyancy: The upward force exerted by a fluid on an immersed or partly immersed body. A body rises or sinks according to its density relative to the surrounding air.Relative density: The ratio of one material’s density to the density of a specified reference material. Air density is an absolute mass-per-volume quantity, whereas relative density is dimensionless and reference-dependent.Atmospheric pressure: The force per unit area exerted by the weight of the atmosphere. Higher pressure compresses air, increasing its mass per unit volume at the same temperature.Aerodynamic drag: The force opposing an object’s motion through a fluid. Air density directly affects the drag force on vehicles and objects moving through air.Volume: The three-dimensional space occupied by a substance or object. Air density is defined by dividing air mass by the volume it occupies.Hydrostatic equilibrium: A state in which pressure gradients balance gravitational forces in a fluid at rest. The vertical air-density profile is tied to the pressure decrease that balances atmospheric weight.Specific gravity: A dimensionless ratio comparing a substance’s density with that of a reference substance. It compares densities rather than giving air’s mass per unit volume directly.Show all 25Linked from 13 pagesKilogram per cubic metreBroader topic: Atmospheric and engineering measurements often express air density in kg/m³.Wing loadingRelated: Air density changes the lift available at a given speed and wing area.Mach numberCompared with: Density alone does not set sound speed in an ideal gas, unlike temperature and composition.Atmospheric dragRelated: Density falls with altitude and directly influences atmospheric drag.Pressure-gradient forceRelated: For a given pressure gradient, density affects the force per unit mass experienced by air.Wind assistanceRelated: Air density affects drag, so equal tailwinds can have different aerodynamic effects.Helmholtz resonanceRelated: Air density contributes to the inertial load of oscillating air in the opening.Air massRelated: Temperature and moisture affect density, influencing whether air rises or sinks.Show all 13