The Density of air reference article from the English Wikipedia on 24-Apr-2004 (provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

Density of air

Density of air ρ tells how much kg (kilogram) mass of air we have in 1 m³, that is (kg/m³). At sea level air is with round 1,3 kg/m³ more compressed by the air masses over it than at more hight. Air is very dense.

At ground level it has always the highest density and the highest air pressure.

Density of air ρ is:

in kg/m³; pressure of air = p, gas constant R, temperature in Kelvin = K

The individuell gas constant R for dry air is:

J = Newton * Meter = N m und T in Kelvin = °C + 273.15

Atmospheric pressure p₀ = 101325 Pa = 1013.25 mbar = 1013.25 hPa and R = 287.05 J/kg·K

At T₀ = 273,15 K at 0°C the density of air is:
ρ₀ = 101325 / 287.05*273.15 = 1.293 kg/m³

At T₂₅ = 293,15 K bei 25°C (normal) the density of air is:
ρ₂₀ = 101325 / 287.05*298,15 = 1.184 kg/m³

We see, the units are very much temperature-sensitive.

p = Sound pressure in N/m² = Pa = Pascal
v = Sound velocity in m/s
J = Sound intensity in W/m²
F = Force in Newton = N
ρ = rho = Density of air in kg/m³
c = Speed of sound in m/s
Z = acoustic impedance in N·s/m³ == Table - Speed of sound in air c, density of air ρ,
acoustic impedance Z vs. temperature °C ==

Impact of temperature
°C	c	ρ	Z
- 10	325.4	1.341	436.5
- 5	328.5	1.316	432.4
0	331.5	1.293	428.3
+ 5	334.5	1.269	424.5
+ 10	337.5	1.247	420.7
+ 15	340.5	1.225	417.0
+ 20	343.4	1.204	413.5
+ 25	346.3	1.184	410.0
+ 30	349.2	1.164	406.6

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