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This must be done by integration. To get the column density, integrate the total column over a height. Per the definition of Dobson units, 1 DU = 0.01 mm of trace gas when compressed down to sea level at standard temperature and pressure. So integrating the number density of air from 0 to 0.01 mm, it becomes equal to 1 DU:
At IUPAC standard temperature and pressure (0 °C and 100 kPa), dry air has a density of approximately 1.2754 kg/m 3. At 20 °C and 101.325 kPa, dry air has a density of 1.2041 kg/m 3. At 70 °F and 14.696 psi, dry air has a density of 0.074887 lb/ft 3.
≡ 1 in/s = 2.54 × 10 −2 m/s: kilometre per hour: km/h ≡ 1 km/h = 2. 7 × 10 −1 m/s knot: kn ≡ 1 nmi/h = 1.852 km/h = 0.51 4 m/s knot (Admiralty) kn ≡ 1 NM (Adm)/h = 1.853 184 km/h [29] = 0.514 77 3 m/s mach number: M: Ratio of the speed to the speed of sound [note 1] in the medium (unitless). ≈ 340 m/s in air at sea level
Density is related to pressure by the ideal gas laws. Therefore, density will also decrease exponentially with height from a sea-level value of ρ 0 roughly equal to 1.2 kg⋅m −3. At an altitude over 100 km, the atmosphere is no longer well-mixed, and each chemical species has its own scale height.
Values of ρ b of b = 1 through b = 6 are obtained from the application of the appropriate member of the pair equations 1 and 2 for the case when h = h b+1. [ 2 ] In these equations, g 0 , M and R * are each single-valued constants, while ρ , L , T and h are multi-valued constants in accordance with the table below.
pure water at 3.984 °C, temperature of its maximum density (1.0000 g/cm 3) [24] 10 2: hM 118.8 M: pure osmium at 20 °C (22.587 g/cm 3) [25] 140.5 M: pure copper at 25 °C (8.93 g/cm 3) 10 3: kM: 10 4: 24 kM: helium in the solar core (150 g/cm 3 ⋅ 65%) [26] 10 5: 10 6: MM: 10 7: 10 8: 122.2 MM: nuclei in a white dwarf from a 3 M ...
The stokes (St) is a unit of kinematic viscosity equal to 1 cm 2 ⋅s −1 (100 mm 2 ⋅s −1). [3] The stilb (sb) is a unit of luminance equal to 1 cd⋅cm −2 (10 kcd⋅m −2). [4] The phot (ph) is a unit of illuminance equal to 1 lm⋅cm −2 (10 klx). [3] The rayl is a unit of specific acoustic impedance, equal to 1 dyn⋅s⋅cm −3 (10 ...
The density of air at sea level is about 1.2 kg/m 3 (1.2 g/L, 0.0012 g/cm 3). Density is not measured directly but is calculated from measurements of temperature, pressure and humidity using the equation of state for air (a form of the ideal gas law). Atmospheric density decreases as the altitude increases.