Thermosphere
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The thermosphere is the layer in the
Earth's atmosphere The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing for ...
directly above the mesosphere and below the exosphere. Within this layer of the atmosphere,
ultraviolet radiation Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30  PHz) to 400 nm (750  THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...
causes
photoionization Photoionization is the physical process in which an ion is formed from the interaction of a photon with an atom or molecule. Cross section Not every interaction between a photon and an atom, or molecule, will result in photoionization. The prob ...
/photodissociation of molecules, creating ions; the thermosphere thus constitutes the larger part of the
ionosphere The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays an ...
. Taking its name from the
Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...
θερμός (pronounced ''thermos'') meaning heat, the thermosphere begins at about 80 km (50 mi) above sea level. At these high altitudes, the residual atmospheric gases sort into strata according to
molecular mass The molecular mass (''m'') is the mass of a given molecule: it is measured in daltons (Da or u). Different molecules of the same compound may have different molecular masses because they contain different isotopes of an element. The related quanti ...
(see turbosphere). Thermospheric
temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...
s increase with altitude due to absorption of highly energetic
solar radiation Solar irradiance is the power per unit area (surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument. Solar irradiance is measured in watts per square metre ( ...
. Temperatures are highly dependent on solar activity, and can rise to or more. Radiation causes the atmospheric particles in this layer to become electrically charged, enabling radio waves to be refracted and thus be received beyond the horizon. In the exosphere, beginning at about 600 km (375 mi) above sea level, the atmosphere turns into
space Space is the boundless three-dimensional extent in which objects and events have relative position and direction. In classical physics, physical space is often conceived in three linear dimensions, although modern physicists usually consider ...
, although, by the judging criteria set for the definition of the Kármán line (100 km), most of the thermosphere is part of space. The border between the thermosphere and exosphere is known as the
thermopause The thermopause is the atmospheric boundary of Earth's energy system, located at the top of the thermosphere. The temperature of the thermopause could range from nearly absolute zero to . Below this, the atmosphere is defined to be active on the i ...
. The highly attenuated gas in this layer can reach during the day. Despite the high temperature, an observer or object will experience low temperatures in the thermosphere, because the extremely low density of the gas (practically a hard
vacuum A vacuum is a space devoid of matter. The word is derived from the Latin adjective ''vacuus'' for "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure. Physicists often dis ...
) is insufficient for the molecules to conduct heat. A normal
thermometer A thermometer is a device that temperature measurement, measures temperature or a temperature gradient (the degree of hotness or coldness of an object). A thermometer has two important elements: (1) a temperature sensor (e.g. the bulb of a merc ...
will read significantly below , at least at night, because the energy lost by thermal radiation would exceed the energy acquired from the atmospheric gas by direct contact. In the anacoustic zone above , the density is so low that molecular interactions are too infrequent to permit the transmission of sound. The dynamics of the thermosphere are dominated by
atmospheric tide Atmospheric tides are global-scale periodic oscillations of the atmosphere. In many ways they are analogous to ocean tides. Atmospheric tides can be excited by: *The regular day–night cycle in the Sun's heating of the atmosphere (insolation) *T ...
s, which are driven predominantly by diurnal heating. Atmospheric waves dissipate above this level because of collisions between the neutral gas and the ionospheric plasma. The thermosphere is uninhabited with the exception of the
International Space Station The International Space Station (ISS) is the largest modular space station currently in low Earth orbit. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos (Russia), JAXA ...
, which orbits the Earth within the middle of the thermosphere between and the Tiangong space station, which orbits between .


Neutral gas constituents

It is convenient to separate the atmospheric regions according to the two temperature minima at an altitude of about (the
tropopause The tropopause is the atmospheric boundary that demarcates the troposphere from the stratosphere; which are two of the five layers of the atmosphere of Earth. The tropopause is a thermodynamic gradient-stratification layer, that marks the end of ...
) and at about (the
mesopause The mesopause is the point of minimum temperature at the boundary between the mesosphere and the thermosphere atmospheric regions. Due to the lack of solar heating and very strong radiative cooling from carbon dioxide, the mesosphere is the cold ...
) (Figure 1). The thermosphere (or the upper atmosphere) is the height region above , while the region between the tropopause and the mesopause is the middle atmosphere (
stratosphere The stratosphere () is the second layer of the atmosphere of the Earth, located above the troposphere and below the mesosphere. The stratosphere is an atmospheric layer composed of stratified temperature layers, with the warm layers of air ...
and mesosphere) where absorption of solar UV radiation generates the temperature maximum near an altitude of and causes the
ozone Ozone (), or trioxygen, is an inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , breaking down in the lo ...
layer. The density of the Earth's atmosphere decreases nearly exponentially with altitude. The total mass of the atmosphere is M = ρA H  ≃ 1 kg/cm2 within a column of one square centimeter above the ground (with ρA = 1.29 kg/m3 the atmospheric density on the ground at z = 0 m altitude, and H ≃ 8 km the average atmospheric
scale height In atmospheric, earth, and planetary sciences, a scale height, usually denoted by the capital letter ''H'', is a distance ( vertical or radial) over which a physical quantity decreases by a factor of e (the base of natural logarithms, approxima ...
). Eighty percent of that mass is concentrated within the
troposphere The troposphere is the first and lowest layer of the atmosphere of the Earth, and contains 75% of the total mass of the planetary atmosphere, 99% of the total mass of water vapour and aerosols, and is where most weather phenomena occur. From ...
. The mass of the thermosphere above about is only 0.002% of the total mass. Therefore, no significant 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 The turbopause, also known as the homopause, marks the altitude in an atmosphere below which turbulent mixing dominates. Mathematically, it is defined as the point where the coefficient of Eddy diffusion is equal to the coefficient of molecular d ...
at about to be a mixture of gases that does not change its composition. Its mean molecular weight is 29 g/mol with molecular oxygen (O2) and nitrogen (N2) as the two dominant constituents. Above the turbopause, however, diffusive separation of the various constituents is significant, so that each constituent follows its barometric height structure with a scale height inversely proportional to its molecular weight. The lighter constituents atomic oxygen (O), helium (He), and hydrogen (H) successively dominate above an altitude of about and vary with geographic location, time, and solar activity. The ratio N2/O which is a measure of the electron density at the ionospheric F region is highly affected by these variations. 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 Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable iso ...
located in a thick band that occurs at the edge of the mesosphere, 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 have begun using this sodium band to create " guide stars" as part of the optical correction process in producing ultra-sharp ground-based observations.


Energy input


Energy budget

The thermospheric temperature can be determined from density observations as well as from direct satellite measurements. The temperature vs. altitude z in Fig. 1 can be simulated by the so-called
Bates Bates may refer to: Places * Bates, Arkansas, an unincorporated community * Bates, Illinois. an unincorporated community in Sangamon County * Bates, Michigan, a community in Grand Traverse County * Bates, New York, a hamlet in the town of Ell ...
profile: (1) T = T_\infty - (T_\infty- T_0) e^ with T the exospheric temperature above about 400 km altitude, To = 355 K, and zo = 120 km reference temperature and height, and s an empirical parameter depending on T and decreasing with T. That formula is derived from a simple equation of heat conduction. One estimates a total heat input of qo≃ 0.8 to 1.6 mW/m2 above zo = 120 km altitude. In order to obtain equilibrium conditions, that heat input qo above zo is lost to the lower atmospheric regions by heat conduction. The exospheric temperature T is a fair measurement of the solar XUV radiation. Since solar radio emission F at 10.7  cm wavelength is a good indicator of solar activity, one can apply the empirical formula for quiet magnetospheric conditions.Hedin, A.E., A revised thermospheric model based on the mass spectrometer and incoherent scatter data: MSIS-83 J. Geophys. Res., 88, 10170, 1983 (2) T_\infty \simeq 500 + 3.4 F_0 with T in K, Fo in 10−2 W m−2 Hz−1 (the Covington index) a value of F averaged over several solar cycles. The Covington index varies typically between 70 and 250 during a solar cycle, and never drops below about 50. Thus, T varies between about 740 and 1350 K. During very quiet magnetospheric conditions, the still continuously flowing magnetospheric energy input contributes by about 250  K to the residual temperature of 500  K in eq.(2). The rest of 250  K in eq.(2) can be attributed to atmospheric waves generated within the troposphere and dissipated within the lower thermosphere.


Solar XUV radiation

The solar X-ray and extreme ultraviolet radiation (XUV) at wavelengths < 170  nm is almost completely absorbed within the thermosphere. This radiation causes the various
ionospheric layer The ionosphere () is the ionized part of the upper atmosphere of Earth, from about to above sea level, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays an im ...
s as well as a temperature increase at these heights (Figure 1). While the solar visible light (380 to 780  nm) is nearly constant with the variability of not more than about 0.1% of the
solar constant The solar constant (''GSC'') is a flux density measuring mean solar electromagnetic radiation (total solar irradiance) per unit area. It is measured on a surface perpendicular to the rays, one astronomical unit (au) from the Sun (roughly the ...
, the solar XUV radiation is highly variable in time and space. For instance, X-ray bursts associated with solar flares can dramatically increase their intensity over preflare levels by many orders of magnitude over some time of tens of minutes. In the extreme ultraviolet, the Lyman α line at 121.6 nm represents an important source of
ionization Ionization, or Ionisation is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged atom or molecul ...
and
dissociation Dissociation, in the wide sense of the word, is an act of disuniting or separating a complex object into parts. Dissociation may also refer to: * Dissociation (chemistry), general process in which molecules or ionic compounds (complexes, or salts ...
at ionospheric D layer heights. During quiet periods of
solar activity Solar phenomena are natural phenomena which occur within the atmosphere of the Sun. These phenomena take many forms, including solar wind, radio wave flux, solar flares, coronal mass ejections, coronal heating and sunspots. These phenomena are ...
, it alone contains more energy than the rest of the XUV spectrum. Quasi-periodic changes of the order 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. During the low solar activity, about half of the total energy input into the thermosphere is thought to be solar XUV radiation. That solar XUV energy input occurs only during daytime conditions, maximizing at the equator during
equinox A solar equinox is a moment in time when the Sun crosses the Earth's equator, which is to say, appears directly above the equator, rather than north or south of the equator. On the day of the equinox, the Sun appears to rise "due east" and se ...
.


Solar wind

The second source of energy input into the thermosphere is
solar wind The solar wind is a stream of charged particles released from the upper atmosphere of the Sun, called the corona. This plasma mostly consists of electrons, protons and alpha particles with kinetic energy between . The composition of the sol ...
energy which is transferred to the magnetosphere by mechanisms that are not well understood. One possible way to transfer energy is via a hydrodynamic dynamo process. Solar wind particles penetrate the polar regions of the magnetosphere where the geomagnetic field lines are essentially vertically directed. An electric field is generated, directed from dawn to dusk. Along the last closed geomagnetic field lines with their footpoints within the
auroral An aurora (plural: auroras or aurorae), also commonly known as the polar lights, is a natural light display in Earth's sky, predominantly seen in high-latitude regions (around the Arctic and Antarctic). Auroras display dynamic patterns of br ...
zones, field-aligned electric currents can flow into the
ionospheric dynamo region In the height region between about 85 and 200 km altitude on Earth, the ionospheric plasma is electrically conducting. Atmospheric tidal winds due to differential solar heating or due to gravitational lunar forcing move the ionospheric plasma ...
where they are closed by electric
Pedersen Pedersen () is a Danish and Norwegian patronymic surname, literally meaning "son of Peder". It is the fourth most common surname in Denmark, shared by about 3.4% of the population, and the sixth most common in Norway. It is of similar origin as th ...
and
Hall current The Hall effect is the production of a voltage difference (the Hall voltage) across an electrical conductor that is transverse to an electric current in the conductor and to an applied magnetic field perpendicular to the current. It was discove ...
s.
Ohm Ohm (symbol Ω) is a unit of electrical resistance named after Georg Ohm. Ohm or OHM may also refer to: People * Georg Ohm (1789–1854), German physicist and namesake of the term ''ohm'' * Germán Ohm (born 1936), Mexican boxer * Jörg Ohm (b ...
ic losses of the Pedersen currents heat the lower thermosphere (see e.g.,
Magnetospheric electric convection field The impact of the solar wind onto the magnetosphere generates an electric field within the inner magnetosphere (r θm) and within the inner magnetosphere (r ≤ 10 a) is the Volland-Stern model (see Fig. 1 a)). The use of an electrostatic ...
). Also, penetration of high energetic particles from the magnetosphere into the auroral regions enhance drastically the electric conductivity, further increasing the electric currents and thus
Joule heating Joule heating, also known as resistive, resistance, or Ohmic heating, is the process by which the passage of an electric current through a conductor (material), conductor produces heat. Joule's first law (also just Joule's law), also known in c ...
. During the quiet magnetospheric activity, the magnetosphere contributes perhaps by a quarter to the thermosphere's energy budget. This is about 250  K of the exospheric temperature in eq.(2). During the very large activity, however, this heat input can increase substantially, by a factor of four or more. That solar wind input occurs mainly in the auroral regions during both day and night.


Atmospheric waves

Two kinds of large-scale atmospheric waves within the lower atmosphere exist: internal waves with finite vertical wavelengths which can transport wave energy upward, and external waves with infinitely large wavelengths that cannot transport wave energy.Volland, H., "Atmospheric Tidal and Planetary Waves", Kluwer, Dordrecht, 1988 Atmospheric gravity waves and most of the
atmospheric tides Atmospheric tides are global-scale periodic oscillations of the atmosphere. In many ways they are analogous to ocean tides. Atmospheric tides can be excited by: *The regular day–night cycle in the Sun's heating of the atmosphere ( insolation) ...
generated within the troposphere belong to the internal waves. Their density amplitudes increase exponentially with height so that at the mesopause these waves become turbulent and their energy is dissipated (similar to breaking of ocean waves at the coast), thus contributing to the heating of the thermosphere by about 250  K in eq.(2). On the other hand, the fundamental diurnal tide labeled (1, −2) which is most efficiently excited by solar irradiance is an external wave and plays only a marginal role within the lower and middle atmosphere. However, at thermospheric altitudes, it becomes the predominant wave. It drives the electric Sq-current within the
ionospheric dynamo region In the height region between about 85 and 200 km altitude on Earth, the ionospheric plasma is electrically conducting. Atmospheric tidal winds due to differential solar heating or due to gravitational lunar forcing move the ionospheric plasma ...
between about 100 and 200  km height. Heating, predominately by tidal waves, occurs mainly at lower and middle latitudes. The variability of this heating depends on the meteorological conditions within the troposphere and middle atmosphere, and may not exceed about 50%.


Dynamics

Within the thermosphere above an altitude of about , all atmospheric waves successively become external waves, and no significant vertical wave structure is visible. The atmospheric wave modes degenerate to the
spherical functions In mathematics and physical science, spherical harmonics are special functions defined on the surface of a sphere. They are often employed in solving partial differential equations in many scientific fields. Since the spherical harmonics form ...
Pnm with m a meridional
wave number In the physical sciences, the wavenumber (also wave number or repetency) is the ''spatial frequency'' of a wave, measured in cycles per unit distance (ordinary wavenumber) or radians per unit distance (angular wavenumber). It is analogous to temp ...
and n the zonal
wave number In the physical sciences, the wavenumber (also wave number or repetency) is the ''spatial frequency'' of a wave, measured in cycles per unit distance (ordinary wavenumber) or radians per unit distance (angular wavenumber). It is analogous to temp ...
(m = 0: zonal mean flow; m = 1: diurnal tides; m = 2: semidiurnal tides; etc.). The thermosphere becomes a damped oscillator system 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 one 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 can be described by a sum of spheric functions: (3) T(\varphi, \lambda, t) = T_\infty \ Here, it is φ latitude, λ longitude, and t time, ωa the
angular frequency In physics, angular frequency "''ω''" (also referred to by the terms angular speed, circular frequency, orbital frequency, radian frequency, and pulsatance) is a scalar measure of rotation rate. It refers to the angular displacement per unit tim ...
of one year, ωd the angular frequency of one solar day, and τ = ωdt + λ the local time. ta = June 21 is the date of northern summer solstice, and τd = 15:00 is the local time of maximum diurnal temperature. The first term in (3) on the right is the global mean of the exospheric temperature (of the order of 1000  K). The second term ith P20 = 0.5(3 sin2(φ)−1)represents the heat surplus at lower latitudes and a corresponding heat deficit at higher latitudes (Fig. 2a). A thermal wind system develops with the wind toward the poles in the upper level and winds away from the poles in the lower level. The coefficient ΔT20 ≈ 0.004 is small because Joule heating in the aurora regions compensates that heat surplus even during quiet magnetospheric conditions. During disturbed conditions, however, that term becomes dominant, changing sign so that now heat surplus is transported from the poles to the equator. The third term (with P10 = sin φ) represents heat surplus on the summer hemisphere and is responsible for the transport of excess heat from the summer into the winter hemisphere (Fig. 2b). Its relative amplitude is of the order ΔT10 ≃ 0.13. The fourth term (with P11(φ) = cos φ) is the dominant diurnal wave (the tidal mode (1,−2)). It is responsible for the transport of excess heat from the daytime hemisphere into the nighttime hemisphere (Fig. 2d). Its relative amplitude is ΔT11≃ 0.15, thus on the order of 150 K. Additional terms (e.g., semiannual, semidiurnal terms, and higher-order terms) must be added to eq.(3). However, they are of minor importance. Corresponding sums can be developed for density, pressure, and the various gas constituents.von Zahn, U., et al., ESRO-4 model of global thermospheric composition and temperatures during low solar activity, Geophy. Res. Lett., ''4'', 33, 1977


Thermospheric storms

In contrast to solar XUV radiation, magnetospheric disturbances, indicated on the ground by geomagnetic variations, show an unpredictable impulsive character, from short periodic disturbances of the order of hours to long-standing giant storms of several days' duration. The reaction of the thermosphere to a large magnetospheric storm is called a thermospheric storm. Since the heat input into the thermosphere occurs at high latitudes (mainly into the auroral regions), the heat transport is represented by the term P20 in eq.(3) is reversed. Also, due to the impulsive form of the disturbance, higher-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 development of an
ionospheric storm Ionospheric storms are storms which contain varying densities of energised electrons produced from the sun. They are categorised into positive and negative storms, where positive storms have a high density of electrons and negative storms contain a ...
is the increase of the ratio N2/O during a thermospheric storm at middle and higher latitude.Prölss, G.W., Density perturbations in the upper atmosphere caused by dissipation of solar wind energy, Surv. Geophys., ''32'', 101, 2011 An increase of N2 increases the loss process of the ionospheric plasma and causes therefore a decrease of the electron density within the ionospheric F-layer (negative ionospheric storm).


Climate change

A contraction of the thermosphere has been observed as a possible result in part due to increased carbon dioxide concentrations, the strongest cooling and contraction occurring in that layer during
solar minimum Solar minimum is the regular period of least solar activity in the Sun's 11-year solar cycle. During solar minimum, sunspot and solar flare activity diminishes, and often does not occur for days at a time. On average, the solar cycle takes abou ...
. The most recent contraction in 2008–2009 was the largest such since at least 1967.


See also

*
Aerial perspective Aerial perspective, or atmospheric perspective, refers to the effect the atmosphere has on the appearance of an object as viewed from a distance. As the distance between an object and a viewer increases, the contrast between the object and its b ...
*
Aeronomy Aeronomy is the scientific study of the upper atmosphere of the Earth and corresponding regions of the atmospheres of other planets. It is a branch of both atmospheric chemistry and atmospheric physics. Scientists specializing in aeronomy, known a ...
*
Air (classical element) Air is one of the four classical elements along with water, earth and fire in ancient Greek philosophy and in Western alchemy. Greek and Roman tradition According to Plato, it is associated with the octahedron; air is considered to be both hot ...
*
Air glow Airglow (also called nightglow) is a faint emission of light by a planetary atmosphere. In the case of Earth's atmosphere, this optical phenomenon causes the night sky never to be completely dark, even after the effects of starlight and dif ...
*
Airshed An airshed is a part of the atmosphere that behaves in a coherent way with respect to the dispersion of emissions. It typically forms an analytical or management unit. Also: a geographic boundary for air-quality standards. Alternatively - an airs ...
*
Atmospheric dispersion modeling Atmospheric dispersion modeling is the mathematical simulation of how air pollutants disperse in the ambient atmosphere. It is performed with computer programs that include algorithms to solve the mathematical equations that govern the pollutant ...
*
Atmospheric electricity Atmospheric electricity is the study of electrical charges in the Earth's atmosphere (or that of another planet). The movement of charge between the Earth's surface, the atmosphere, and the ionosphere is known as the global atmospheric electr ...
*
Atmospheric Radiation Measurement Climate Research Facility The Atmospheric Radiation Measurement Climate Research Facility (ARM Climate Research Facility) is a multi-laboratory United States Department of Energy scientific user facility used for national and international global climate research efforts. ...
(ARM) (in the U.S.) *
Atmospheric stratification The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing for ...
*
Biosphere The biosphere (from Greek βίος ''bíos'' "life" and σφαῖρα ''sphaira'' "sphere"), also known as the ecosphere (from Greek οἶκος ''oîkos'' "environment" and σφαῖρα), is the worldwide sum of all ecosystems. It can also be ...
*
Climate system Earth's climate system is a complex system having five interacting components: the atmosphere (air), the hydrosphere (water), the cryosphere (ice and permafrost), the lithosphere (earth's upper rocky layer) and the biosphere (living things). '' ...
**
Earth's energy budget Earth's energy budget accounts for the balance between the energy that Earth receives from the Sun and the energy the Earth loses back into outer space. Smaller energy sources, such as Earth's internal heat, are taken into consideration, but m ...
* COSPAR international reference atmosphere (CIRA) *
Environmental impact of aviation Like other emissions resulting from fossil fuel combustion, aircraft engines produce gases, noise, and particulates, raising environmental concerns over their global effects and their effects on local air quality. Jet airliners contribute to ...
*
Global dimming Global dimming is the reduction in the amount of global direct irradiance at the Earth's surface that has been observed since systematic measurements began in the 1950s. The effect varies by location, but worldwide it has been estimated to be of ...
* Historical temperature record *
Hydrosphere The hydrosphere () is the combined mass of water found on, under, and above the surface of a planet, minor planet, or natural satellite. Although Earth's hydrosphere has been around for about 4 billion years, it continues to change in shape. This ...
*
Hypermobility (travel) Hypermobile travelers are "highly mobile individuals" who take "frequent trips, often over great distances." They "account for a large share of the overall kilometres travelled, especially by air." These people contribute significantly to the overal ...
*
Kyoto Protocol The Kyoto Protocol was an international treaty which extended the 1992 United Nations Framework Convention on Climate Change (UNFCCC) that commits state parties to reduce greenhouse gas emissions, based on the scientific consensus that (part ...
*
Leaching (agriculture) In agriculture, leaching is the loss of water-soluble plant nutrients from the soil, due to rain and irrigation. Soil structure, crop planting, type and application rates of fertilizers, and other factors are taken into account to avoid excessive ...
*
Lithosphere A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust (geology), crust and the portion of the upper mantle (geology), mantle that behaves elastically on time sca ...
*
Reference atmospheric model A reference atmospheric model describes how the ideal gas properties (namely: pressure, temperature, density, and molecular weight) of an atmosphere change, primarily as a function of altitude, and sometimes also as a function of latitude, day of ...


References

{{Authority control Atmosphere of Earth Atmosphere