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These figures should be compared with the temperature and density of Earth's atmosphere plotted at NRLMSISE-00, which shows the air density dropping from 1200 g/m 3 at sea level to 0.125 g/m 3 at 70 km, a factor of 9600, indicating an average scale height of 70 / ln(9600) = 7.64 km, consistent with the indicated average air temperature over ...
To calculate the density of air as a function of altitude, one requires additional parameters. For the troposphere, the lowest part (~10 km) of the atmosphere, they are listed below, along with their values according to the International Standard Atmosphere, using for calculation the universal gas constant instead of the air specific constant:
The NASA Earth Global Reference Atmospheric Model (Earth-GRAM) was developed by the Marshall Space Flight Center to provide a design reference atmosphere that, unlike the standard atmospheres, allows for geographical variability, a wide range of altitudes (surface to orbital altitudes), and different months and times of day. It can also ...
The troposphere is the lowest layer of Earth's atmosphere. It extends from Earth's surface to an average height of about 12 km (7.5 mi; 39,000 ft), although this altitude varies from about 9 km (5.6 mi; 30,000 ft) at the geographic poles to 17 km (11 mi; 56,000 ft) at the Equator, [17] with some variation due
The COSPAR International Reference Atmosphere (CIRA) 2012 and the ISO 14222 Earth Atmosphere Density standard both recommend NRLMSISE-00 for composition uses. JB2008 is a newer model of the Earth's atmosphere from 120 km to 2000 km, developed by the US Air Force Space Command and Space Environment Technologies taking into account realistic ...
Since the atmosphere at a height of approximately 5.5 kilometres (3.4 mi) is mostly divergence-free, the barotropic model best approximates the state of the atmosphere at a geopotential height corresponding to that altitude, which corresponds to the atmosphere's 500 mb (15 inHg) pressure surface. [6]
The density of the Earth's atmosphere decreases nearly exponentially with altitude. The total mass of the atmosphere is M = ρ A H ≃ 1 kg/cm 2 within a column of one square centimeter above the ground (with ρ A = 1.29 kg/m 3 the atmospheric density on the ground at z = 0 m altitude, and H ≃ 8 km the average atmospheric scale height).
The hypsometric equation, also known as the thickness equation, relates an atmospheric pressure ratio to the equivalent thickness of an atmospheric layer considering the layer mean of virtual temperature, gravity, and occasionally wind. It is derived from the hydrostatic equation and the ideal gas law.