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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).
These layers are the troposphere, stratosphere, mesosphere, and thermosphere. The troposphere is the lowest of the four layers and extends from the surface of the Earth to about 11 km (6.8 mi) into the atmosphere, where the tropopause (the boundary between the troposphere stratosphere) is located. The width of the troposphere can vary depending ...
The thermosphere is the second-highest layer of Earth's atmosphere. It extends from the mesopause (which separates it from the mesosphere) at an altitude of about 80 km (50 mi; 260,000 ft) up to the thermopause at an altitude range of 500–1000 km (310–620 mi
The increase in altitude necessary for P or ρ to drop to 1/e of its initial value is called the scale height: H = R T M g 0 {\displaystyle H={\frac {RT}{Mg_{0}}}} where R is the ideal gas constant, T is temperature, M is average molecular weight, and g 0 is the gravitational acceleration at the planet's surface.
at each geopotential altitude, where g is the standard acceleration of gravity, and R specific is the specific gas constant for dry air (287.0528J⋅kg −1 ⋅K −1). The solution is given by the barometric formula. Air density must be calculated in order to solve for the pressure, and is used in calculating dynamic pressure for moving vehicles.
Comparison of the 1962 US Standard Atmosphere graph of geometric altitude against air density, pressure, the speed of sound and temperature with approximate altitudes of various objects. [ 1 ] The U.S. Standard Atmosphere is a static atmospheric model of how the pressure , temperature , density , and viscosity of the Earth's atmosphere change ...
The mesosphere ranges from 50 km to 85 km and is the layer wherein most meteors are incinerated before reaching the surface. The thermosphere extends from an altitude of 85 km to the base of the exosphere at 690 km and contains the ionosphere, where solar radiation ionizes the atmosphere. The density of the ionosphere is greater at short ...
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.