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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).
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
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] Atmospheric temperature is a measure of temperature at different levels of the Earth's atmosphere.
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 ...
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.
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 ...
Presently "CIRA 1986" or CIRA-86 covers the height range up to 120 km as a set of tables. In the thermosphere, above about 100 km, CIRA-86 is identical to the more complicated NASA MSIS-86 model. All models are now available on the Web. The task group takes account of more recent data at bi-annual meetings in connection to COSPAR meeting.
The Mesosphere, Lower Thermosphere and Ionosphere (MLTI) region of the atmosphere to be studied by TIMED is located between 60 and 180 kilometres (37 and 112 mi) above the Earth's surface, where energy from solar radiation is first deposited into the atmosphere. This can have profound effects on Earth's upper atmospheric regions, particularly ...