Air Density from Relative Humidity, Pressure, and Temperature Calculator
What is Air Density Calculation from Relative Humidity, Pressure, and Temperature?
Air density can be influenced by temperature, pressure, and relative humidity. As relative humidity increases, air density decreases because the water vapor is less dense than dry air. The general equation takes into account the specific gas constants for both dry air and water vapor, as well as the partial pressure of water vapor.
Formula:
ρ = (P – e) / (R₁ × T) + e / (R₂ × T)
Where:
- ρ = Air density in kg/m³
- P = Total pressure in Pascal (Pa)
- e = Partial pressure of water vapor in Pa
- R₁ = Specific gas constant for dry air (287.05 J/(kg·K))
- R₂ = Specific gas constant for water vapor (461.5 J/(kg·K))
- T = Temperature in Kelvin (converted from Celsius)
| Temperature (°C) | Pressure (Pa) | Relative Humidity (%) | Air Density (kg/m³) | Formula |
|---|---|---|---|---|
| 20 | 101325 | 50 | 1.1634 | ρ = (101325 – 1121.02) / (287.05 × 293.15) + 1121.02 / (461.5 × 293.15) = 1.1634 |
| 25 | 101325 | 60 | 1.1542 | ρ = (101325 – 1345.37) / (287.05 × 298.15) + 1345.37 / (461.5 × 298.15) = 1.1542 |
| 30 | 101325 | 70 | 1.1450 | ρ = (101325 – 1570.72) / (287.05 × 303.15) + 1570.72 / (461.5 × 303.15) = 1.1450 |