what is the distance from the thermosphere to the earth

Layer of the Globe'southward temper higher up the mesosphere and below the exosphere

Earth atmosphere diagram showing all the layers of the atmosphere to scale

The thermosphere is the layer in the Earth's atmosphere directly to a higher place the mesosphere and below the exosphere. Within this layer of the atmosphere, ultraviolet radiation causes photoionization/photodissociation of molecules, creating ions; the thermosphere thus constitutes the larger part of the ionosphere. Taking its name from the Greek θερμός (pronounced thermos) meaning estrus, the thermosphere begins at most 80 km (fifty mi) above sea level.^[i] At these loftier altitudes, the residual atmospheric gases sort into strata co-ordinate to molecular mass (see turbosphere). Thermospheric temperatures increase with altitude due to absorption of highly energetic solar radiation. Temperatures are highly dependent on solar activity, and can rise to 2,000 °C (3,630 °F) or more. Radiation causes the temper particles in this layer to become electrically charged particles, enabling radio waves to be refracted and thus be received beyond the horizon. In the exosphere, beginning at about 600 km (375 mi) above bounding main level, the temper turns into space, although, by the judging criteria set for the definition of the Kármán line, the thermosphere itself is part of space. The edge between the thermosphere and exosphere is known every bit the thermopause.

The highly attenuated gas in this layer can reach two,500 °C (4,530 °F) during the twenty-four hours. Despite the loftier temperature, an observer or object will experience cold temperatures in the thermosphere, because the extremely depression density of the gas (practically a difficult vacuum) is bereft for the molecules to conduct heat. A normal thermometer will read significantly below 0 °C (32 °F), at least at night, because the energy lost by thermal radiation would exceed the free energy acquired from the atmospheric gas past direct contact. In the anacoustic zone to a higher place 160 kilometres (99 mi), the density is so depression that molecular interactions are too infrequent to permit the transmission of audio.

The dynamics of the thermosphere are dominated by atmospheric tides, which are driven predominantly past diurnal heating. Atmospheric waves misemploy higher up this level because of collisions betwixt the neutral gas and the ionospheric plasma.

The thermosphere is uninhabited with the exception of the International Space Station, which orbits the Earth within the middle of the thermosphere betwixt 408 and 410 kilometres (254 and 255 mi) and the Tiangong space station, which orbits between 340 and 450 kilometres (210 and 280 mi).

Neutral gas constituents [edit]

Information technology is user-friendly to dissever the atmospheric regions according to the two temperature minima at an distance of about 12 kilometres (vii.v mi) (the tropopause) and at well-nigh 85 kilometres (53 mi) (the mesopause) (Effigy ane). The thermosphere (or the upper atmosphere) is the height region above 85 kilometres (53 mi), while the region betwixt the tropopause and the mesopause is the eye atmosphere (stratosphere and mesosphere) where absorption of solar UV radiations generates the temperature maximum nearly an altitude of 45 kilometres (28 mi) and causes the ozone layer.

Figure ane. Nomenclature of atmospheric regions based on the profiles of electrical electrical conductivity (left), temperature (heart), and electron number density in thousand⁻ⁱⁱⁱ(right)

The density of the Earth's atmosphere decreases near exponentially with altitude. The total mass of the atmosphere is Grand = ρ_A H  ≃ 1 kg/cm² within a column of ane foursquare centimeter above the ground (with ρ_A = 1.29 kg/m^three the atmospheric density on the ground at z = 0 m altitude, and H ≃ 8 km the average atmospheric scale height). Eighty percent of that mass is concentrated within the troposphere. The mass of the thermosphere in a higher place about 85 kilometres (53 mi) is only 0.002% of the total mass. Therefore, no pregnant energetic feedback from the thermosphere to the lower atmospheric regions can be expected.

Turbulence causes the air within the lower atmospheric regions below the turbopause at about 110 kilometres (68 mi) to be a mixture of gases that does not change its composition. Its mean molecular weight is 29 k/mol with molecular oxygen (O₂) and nitrogen (Northward₂) as the two dominant constituents. Higher up the turbopause, however, diffusive separation of the various constituents is significant, so that each constituent follows its barometric tiptop structure with a calibration top inversely proportional to its molecular weight. The lighter constituents atomic oxygen (O), helium (He), and hydrogen (H) successively dominate higher up an altitude of about 200 kilometres (124 mi) and vary with geographic location, fourth dimension, and solar activity. The ratio Northward₂/O which is a measure of the electron density at the ionospheric F region is highly affected past these variations.^[2] These changes follow from the diffusion of the minor constituents through the major gas component during dynamic processes.

The thermosphere contains an appreciable concentration of elemental sodium located in a ten-kilometre (6.2 mi) thick ring that occurs at the edge of the mesosphere, 80 to 100 kilometres (l to 62 mi) above Earth's surface. The sodium has an average concentration of 400,000 atoms per cubic centimeter. This band is regularly replenished by sodium sublimating from incoming meteors. Astronomers take begun using this sodium band to create "guide stars" as part of the optical correction process in producing ultra-precipitous ground-based observations.^[3]

Energy input [edit]

Energy upkeep [edit]

The thermospheric temperature tin be determined from density observations likewise as from direct satellite measurements. The temperature vs. altitude z in Fig. 1 can be simulated by the so-chosen Bates contour:^[4]

(1) ${\displaystyle T=T_{\infty }-(T_{\infty }-T_{0})e^{-south(z-z_{0})}}$

with T_∞ the exospheric temperature above about 400 km altitude, T_o = 355 Yard, and z_o = 120 km reference temperature and peak, and s an empirical parameter depending on T_∞ and decreasing with T_∞. That formula is derived from a unproblematic equation of heat conduction. One estimates a total heat input of q_o≃ 0.8 to ane.6 mW/thousand² above z_o = 120 km altitude. In order to obtain equilibrium weather condition, that estrus input q_o above z_o is lost to the lower atmospheric regions by rut conduction.

The exospheric temperature T_∞ is a off-white measurement of the solar XUV radiations. Since solar radio emission F at 10.seven  cm wavelength is a adept indicator of solar activity, one tin can apply the empirical formula for quiet magnetospheric conditions.^[5]

(two) ${\displaystyle T_{\infty }\simeq 500+3.4F_{0}}$

with T_∞ in K, F_o in 10⁻ⁱⁱ W g⁻² Hz^−one (the Covington index) a value of F averaged over several solar cycles. The Covington index varies typically betwixt lxx and 250 during a solar cycle, and never drops below about l. Thus, T_∞ varies between virtually 740 and 1350 Thousand. During very repose magnetospheric conditions, the still continuously flowing magnetospheric energy input contributes by well-nigh 250  K to the balance temperature of 500  K in eq.(ii). The rest of 250  G in eq.(2) can be attributed to atmospheric waves generated within the troposphere and dissipated within the lower thermosphere.

Solar XUV radiation [edit]

The solar X-ray and extreme ultraviolet radiation (XUV) at wavelengths < 170  nm is near completely absorbed within the thermosphere. This radiation causes the various ionospheric layers as well every bit a temperature increase at these heights (Figure 1). While the solar visible light (380 to 780  nm) is nearly abiding with the variability of non more than about 0.1% of the solar constant,^[half-dozen] the solar XUV radiation is highly variable in time and space. For instance, Ten-ray bursts associated with solar flares tin dramatically increase their intensity over preflare levels past many orders of magnitude over some time of tens of minutes. In the extreme ultraviolet, the Lyman α line at 121.half dozen nm represents an important source of ionization and dissociation at ionospheric D layer heights.^[seven] During quiet periods of solar action, it alone contains more free energy than the residue of the XUV spectrum. Quasi-periodic changes of the guild of 100% or greater, with periods of 27 days and 11 years, belong to the prominent variations of solar XUV radiation. However, irregular fluctuations over all time scales are present all the time.^[8] During the low solar activity, about one-half of the total energy input into the thermosphere is thought to exist solar XUV radiation. That solar XUV energy input occurs only during daytime conditions, maximizing at the equator during equinox.

Solar air current [edit]

The 2nd source of energy input into the thermosphere is solar current of air energy which is transferred to the magnetosphere by mechanisms that are non well understood. One possible way to transfer free energy is via a hydrodynamic dynamo process. Solar air current particles penetrate the polar regions of the magnetosphere where the geomagnetic field lines are essentially vertically directed. An electrical field is generated, directed from dawn to sunset. Forth the final closed geomagnetic field lines with their footpoints within the auroral zones, field-aligned electric currents tin can menstruation into the ionospheric dynamo region where they are closed by electric Pedersen and Hall currents. Ohmic losses of the Pedersen currents heat the lower thermosphere (run into e.g., Magnetospheric electric convection field). As well, penetration of high energetic particles from the magnetosphere into the auroral regions enhance drastically the electric electrical conductivity, further increasing the electric currents and thus Joule heating. During the quiet magnetospheric activeness, the magnetosphere contributes perchance by a quarter to the thermosphere'due south energy budget.^[9] This is about 250  Thousand of the exospheric temperature in eq.(2). During the very large activity, however, this heat input can increment substantially, by a gene of iv or more. That solar air current input occurs mainly in the auroral regions during both day and night.

Atmospheric waves [edit]

Ii kinds of large-calibration atmospheric waves within the lower atmosphere exist: internal waves with finite vertical wavelengths which can transport wave energy upwards, and external waves with infinitely large wavelengths that cannot transport wave energy.^[10] Atmospheric gravity waves and most of the atmospheric tides generated within the troposphere belong to the internal waves. Their density amplitudes increase exponentially with pinnacle so that at the mesopause these waves become turbulent and their energy is dissipated (similar to breaking of body of water waves at the coast), thus contributing to the heating of the thermosphere past about 250  K in eq.(ii). On the other hand, the fundamental diurnal tide labeled (ane, −ii) which is well-nigh efficiently excited by solar irradiance is an external wave and plays only a marginal function within the lower and middle atmosphere. Still, at thermospheric altitudes, information technology becomes the predominant wave. It drives the electrical Sq-current within the ionospheric dynamo region between about 100 and 200  km summit.

Heating, predominately by tidal waves, occurs mainly at lower and centre latitudes. The variability of this heating depends on the meteorological conditions within the troposphere and centre temper, and may not exceed almost 50%.

Dynamics [edit]

Effigy 2. Schematic meridian-elevation cross-department of apportionment of (a) symmetric wind component (P₂ ⁰), (b) of antisymmetric current of air component (P₁ ⁰), and (d) of symmetric diurnal wind component (P_one ^one) at 3 h and 15 h local time. Upper right panel (c) shows the horizontal wind vectors of the diurnal component in the northern hemisphere depending on local fourth dimension.

Within the thermosphere to a higher place an altitude of most 150 kilometres (93 mi), all atmospheric waves successively get external waves, and no significant vertical moving ridge structure is visible. The atmospheric wave modes degenerate to the spherical functions P_n ^thousand with chiliad a meridional wave number and n the zonal moving ridge number (yard = 0: zonal hateful flow; one thousand = ane: diurnal tides; grand = two: semidiurnal tides; etc.). The thermosphere becomes a damped oscillator organisation with low-pass filter characteristics. This means that smaller-scale waves (greater numbers of (n,m)) and higher frequencies are suppressed in favor of large-scale waves and lower frequencies. If ane considers very quiet magnetospheric disturbances and a constant mean exospheric temperature (averaged over the sphere), the observed temporal and spatial distribution of the exospheric temperature distribution tin can exist described past a sum of spheric functions:^[11]

(3) ${\displaystyle T(\varphi ,\lambda ,t)=T_{\infty }\{1+\Delta T_{two}^{0}P_{2}^{0}(\varphi )+\Delta T_{one}^{0}P_{1}^{0}(\varphi )\cos[\omega _{a}(t-t_{a})]+\Delta T_{1}^{ane}P_{ane}^{i}(\varphi )\cos(\tau -\tau _{d})+\cdots \}}$

Here, it is φ breadth, λ longitude, and t time, ω_a the athwart frequency of one year, ω_d the angular frequency of one solar day, and τ = ω_dt + λ the local time. t_a = June 21 is the appointment of northern summer solstice, and τ_d = 15:00 is the local time of maximum diurnal temperature.

The offset term in (3) on the right is the global hateful of the exospheric temperature (of the club of 1000  Chiliad). The 2nd term [with P₂ ⁰ = 0.5(iii sin^two(φ)−1)] represents the estrus surplus at lower latitudes and a corresponding heat arrears at college latitudes (Fig. 2a). A thermal wind system develops with the wind toward the poles in the upper level and winds abroad from the poles in the lower level. The coefficient ΔT_two ⁰ ≈ 0.004 is small considering Joule heating in the aurora regions compensates that heat surplus even during placidity magnetospheric conditions. During disturbed conditions, all the same, that term becomes ascendant, changing sign so that at present heat surplus is transported from the poles to the equator. The third term (with P_one ⁰ = sin φ) represents heat surplus on the summertime hemisphere and is responsible for the transport of excess heat from the summertime into the winter hemisphere (Fig. 2b). Its relative amplitude is of the lodge ΔT₁ ⁰ ≃ 0.xiii. The 4th term (with P_ane ¹(φ) = cos φ) is the dominant diurnal moving ridge (the tidal mode (1,−two)). Information technology is responsible for the ship of excess estrus from the daytime hemisphere into the nighttime hemisphere (Fig. 2d). Its relative amplitude is ΔT₁ ¹≃ 0.fifteen, thus on the order of 150 K. Additional terms (e.one thousand., semiannual, semidiurnal terms, and college-social club terms) must be added to eq.(iii). All the same, they are of minor importance. Corresponding sums can exist developed for density, pressure, and the diverse gas constituents.^{[5] [12]}

Thermospheric storms [edit]

In dissimilarity to solar XUV radiation, magnetospheric disturbances, indicated on the ground past geomagnetic variations, show an unpredictable impulsive character, from short periodic disturbances of the guild of hours to long-continuing giant storms of several days' duration. The reaction of the thermosphere to a large magnetospheric tempest is called a thermospheric tempest. Since the heat input into the thermosphere occurs at loftier latitudes (mainly into the auroral regions), the heat transport is represented past the term P_two ⁰ in eq.(3) is reversed. Also, due to the impulsive form of the disturbance, college-order terms are generated which, however, possess short decay times and thus quickly disappear. The sum of these modes determines the "travel time" of the disturbance to the lower latitudes, and thus the response time of the thermosphere with respect to the magnetospheric disturbance. Important for the evolution of an ionospheric storm is the increase of the ratio Northward_ii/O during a thermospheric storm at middle and higher latitude.^[13] An increase of N₂ increases the loss process of the ionospheric plasma and causes therefore a subtract of the electron density within the ionospheric F-layer (negative ionospheric storm).

Climate alter [edit]

A contraction of the thermosphere has been observed as a possible effect in part due to increased carbon dioxide concentrations, the strongest cooling and contraction occurring in that layer during solar minimum. The virtually recent contraction in 2008–2009 was the largest such since at least 1967.^{[fourteen] [15] [16]}

See likewise [edit]

• Aeriform perspective
• Aeronomy
• Air (classical element)
• Air glow
• Airshed
• Atmospheric dispersion modeling
• Atmospheric electricity
• Atmospheric Radiation Measurement Climate Inquiry Facility (ARM) (in the U.S.)
• Atmospheric stratification
• Biosphere
• Climate system
  • Globe'due south energy budget
• COSPAR international reference temper (CIRA)
• Environmental impact of aviation
• Global dimming
• Historical temperature tape
• Hydrosphere
• Hypermobility (travel)
• Kyoto Protocol
• Leaching (agriculture)
• Lithosphere
• Reference atmospheric model

References [edit]

1. ^ Duxbury & Duxbury (1997). Introduction to the World's Oceans (5th ed.).
2. ^ Prölss, G.W., and G. K. Bird, "Physics of the Earth'southward Space Environment", Springer Verlag, Heidelberg, 2010
3. ^ "Martin Enderlein et al., ESO's Very Large Telescope sees four times showtime light, Laser Focus Earth, July 2016, pp. 22-24".
4. ^ Rawer, 1000., Modelling of neutral and ionized atmospheres, in Flügge, S. (ed): Encycl. Phys., 49/7, Springer Verlag, Heidelberg, 223
5. ^ ^{a b} Hedin, A.E., A revised thermospheric model based on the mass spectrometer and breathless besprinkle data: MSIS-83 J. Geophys. Res., 88, 10170, 1983
6. ^ Willson, R.C., Measurements of the solar total irradiance and its variability, Space Sci. Rev., 38, 203, 1984
7. ^ Brasseur, One thousand., and S. Salomon, "Aeronomy of the Middle Atmosphere", Reidel Pub., Dordrecht, 1984
8. ^ Schmidtke, G., Modelling of the solar radiation for aeronomical applications, in Flügge, S. (ed), Encycl. Phys. 49/7, Springer Verlag, Heidelberg, 1
9. ^ Knipp, D.J., W.K. Tobiska, and B.A. Emery, Directly and indirect thermospheric heating source for solar cycles, Solar Phys., 224, 2506, 2004
10. ^ Volland, H., "Atmospheric Tidal and Planetary Waves", Kluwer, Dordrecht, 1988
11. ^ Köhnlein, W., A model of thermospheric temperature and composition, Planet. Space Sci. 28, 225, 1980
12. ^ von Zahn, U., et al., ESRO-4 model of global thermospheric composition and temperatures during low solar activity, Geophy. Res. Lett., iv, 33, 1977
13. ^ Prölss, G.Westward., Density perturbations in the upper temper caused by dissipation of solar air current energy, Surv. Geophys., 32, 101, 2011
14. ^ Scientific discipline News, NASA (2010-07-15). "A Puzzling Collapse of Earth's Upper Atmosphere". National Aeronautics and Space Administration - Scientific discipline News . Retrieved 2010-07-16 .
15. ^ Ho, Derrick (2010-07-17). "Scientists baffled by unusual upper atmosphere shrinkage". Cable News Network . Retrieved 2010-07-18 .
16. ^

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Source: https://en.wikipedia.org/wiki/Thermosphere

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