Our modern atmosphere is divided into the troposphere, where we live, then the stratosphere, mesosphere and thermosphere.
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The thermosphere, which extends from about 53 to 375 miles above the Earth is home to the ISS.
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It also affects the radiative cooling from the carbon-dioxide bands in the Martian thermosphere, which is above the mesosphere.
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In its high-altitude thermosphere, temperatures can range between 700 degrees Kelvin (426 degrees Celsius) and 1,000 degrees Kelvin (726 degrees Celsius).
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When it is not jokingly referred to as the ignorosphere, this atmospheric layer is called the mesosphere-lower thermosphere-ionosphere (MLTI) region.
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Adams was sent to test the X-15's altitude limits, and was able to climb 0003 miles above Earth, into the Thermosphere.
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This boundary is somewhat arbitrary, but it's located between the mesosphere and the thermosphere—a kind of end-of-the-line for the atmosphere.
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The startup has launched nearly a dozen demo flights of its New Shepard rocket, which is designed to send tourists on scenic trips to the thermosphere.
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Satellites do different things — take pictures, transmit data and provide all types of surveillance — but they're all ORBITAL, most of them circling Earth in the thermosphere.
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Micrometeorites entering our atmosphere today chemically interact with the upper mesosphere and lower thermosphere Typically, space debris burns up in our atmosphere and becomes the shooting stars we see at night.
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At this boundary, near the bottom of the thermosphere, the atmosphere is so thin that principles of aeronautic flight no longer apply, and a vehicle at this altitude must move faster than orbital velocity to achieve lift.
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Three types of cubesats are the Australian contribution to the international QB193 mission, in which 36 satellites from different institutions around the world will carry instruments provided by the Von Karman Institute (VKI) to examine the lower thermosphere.
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Bezos' money, earned from Amazon, has paid for the building where he sits, the air-conditioning, and the 60-foot rocket lying on its side in a nearby hangar, waiting to be tugged to a launchpad and shot into the thermosphere.
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The thermosphere is completely uninhabited with the exception of the International Space Station. The International Space Station orbits the Earth within the middle of the thermosphere, between .
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In it temperature decreases with height reaching a minimum of about 36 K at the tropopause. There is no stratosphere, defined as a layer where heating from the warmer troposphere and thermosphere is balanced by radiative cooling. Higher regions include the thermosphere (8–850 km) and exosphere (above 850 km). In the thermosphere the temperature rises reaching a constant value of about 95 K above 300 km.
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80% of that mass is concentrated within the troposphere. The mass of the thermosphere above about 85 km is only 0.002% of the total mass. Therefore, no significant energetic feedback from the thermosphere to the lower atmospheric regions can be expected.
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It is the coldest part of the Venusian dayside atmosphere. In the dayside mesopause, which serves as a boundary between the mesosphere and thermosphere and is located between 95–120 km, temperature increases to a constant—about 300–400 K (27–127 °C)—value prevalent in the thermosphere. In contrast, the nightside Venusian thermosphere is the coldest place on Venus with temperature as low as 100 K (−173 °C). It is even called a cryosphere.
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Earth atmosphere diagram showing all the layers of the atmosphere to scale The thermosphere is the layer in the Earth's atmosphere directly above 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 heat, the thermosphere begins at about 80 km (50 mi) above sea level.Duxbury & Duxbury.
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The TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics) is an orbiter mission dedicated to study the dynamics of the Mesosphere and Lower Thermosphere (MLT) portion of the Earth's atmosphere. The mission was launched from Vandenberg Air Force Base in California on December 7, 2001 aboard a Delta II rocket launch vehicle.
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As the package reaches the Matrian thermosphere continuous tracking would commence in order to verify mechanism deployment during descent.
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The lower part of the thermosphere, from above Earth's surface, contains the ionosphere. The temperature of the thermosphere gradually increases with height. Unlike the stratosphere beneath it, wherein a temperature inversion is due to the absorption of radiation by ozone, the inversion in the thermosphere occurs due to the extremely low density of its molecules. The temperature of this layer can rise as high as , though the gas molecules are so far apart that its temperature in the usual sense is not very meaningful.
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The Ionosphere-Thermosphere Storm Probes (I-TSP) is a NASA mission which will study the ionosphere and the thermosphere. This mission is part of the Living With a Star program, the second mission in a pair of geospace missions. The first mission is the Radiation Belt Storm Probes, which were launched in August 2012.
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NASA also reported that these powerful flares heated the Earth's upper atmosphere with the biggest dose of infrared radiation since 2005. From March 8 to March 10, the thermosphere absorbed 26 billion kWh of energy. Infrared radiation from carbon dioxide and nitric oxide, the two most efficient coolants in the thermosphere, re-radiated 95% of that total back into space.
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Damping of the tides occurs primarily in the lower thermosphere region, and may be caused by turbulence from breaking gravity waves. A similar phenomena to ocean waves breaking on a beach, the energy dissipates into the background atmosphere. Molecular diffusion also becomes increasingly important at higher levels in the lower thermosphere as the mean free path increases in the rarefied atmosphere.Forbes, J.M., et al.
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The geomagnetic storm adds heat to the thermosphere, causing the thermosphere to expand and rise, increasing the drag on spacecraft. The 2009 satellite collision between the Iridium 33 and Cosmos 2251 demonstrated the importance of having precise knowledge of all objects in orbit. Iridium 33 had the capability to maneuver out of the path of Cosmos 2251 and could have evaded the crash, if a credible collision prediction had been available.
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The outermost layer of the Uranian atmosphere, extending for thousands of kilometres, is the thermosphere/exosphere, which has a uniform temperature of around 800 to 850 K. This is much higher than, for instance, the 420 K observed in the thermosphere of Saturn. The heat sources necessary to sustain such high temperatures are not understood, since neither solar FUV/EUV radiation nor auroral activity can provide the necessary energy. The weak cooling efficiency due to the depletion of hydrocarbons in the stratosphere may contribute to this phenomenon. In addition to molecular hydrogen, the thermosphere contains a large proportion of free hydrogen atoms, while helium is thought to be absent here, because it separates diffusively at lower altitudes.
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The energetic particles coming from Jupiter's magnetosphere create bright auroral ovals, which encircle the poles. Unlike their terrestrial analogs, which appear only during magnetic storms, aurorae are permanent features of Jupiter's atmosphere. The thermosphere was the first place outside the Earth where the trihydrogen cation () was discovered. This ion emits strongly in the mid-infrared part of the spectrum, at wavelengths between 3 and 5 μm; this is the main cooling mechanism of the thermosphere.
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However, the aurora borealis and aurora australis sometimes occur in the lower part of the exosphere, where they overlap into the thermosphere. The exosphere contains most of the satellites orbiting Earth.
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The scientific objectives of the GOLD mission are to determine how geomagnetic storms alter the temperature and composition of Earth's atmosphere, to analyze the global-scale response of the thermosphere to solar extreme-ultraviolet variability, to investigate the significance of atmospheric waves and tides propagating from below the temperature structure of the thermosphere and to resolve how the structure of the equatorial ionosphere influences the formation and evolution of equatorial plasma density irregularities. The viewpoint provided by GOLD geostationary orbit – from which the same hemisphere is always observable – is a new perspective on the Earth's upper atmosphere. This viewpoint allows local time, universal time and longitudinal variations of the thermosphere and ionosphere's response to the various forcing mechanisms to be uniquely determined.
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The Thermosphere Ionosphere Mesosphere Energetics and Dynamics, or TIMED, mission explores Earth's mesosphere and lower thermosphere (40–50 miles up), the least explored and understood region of the atmosphere. Solar events, as well as temperature changes in the stratosphere can perturb this region, but the overall structure of and responses to these effects are not understood. Advances in remote sensing technology employed by TIMED enable it to explore this region on a global basis from space.
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Although the thermosphere has a high proportion of molecules with high energy, it would not feel hot to a human in direct contact, because its density is too low to conduct a significant amount of energy to or from the skin. This layer is completely cloudless and free of water vapor. However, non-hydrometeorological phenomena such as the aurora borealis and aurora australis are occasionally seen in the thermosphere. The International Space Station orbits in this layer, between .
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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.
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Atmospheric tides dominate the dynamics of the mesosphere and lower thermosphere, essential to understanding the atmosphere as a whole. Other phenomena studied are upper-atmospheric lightning discharges, such as red sprites, sprite halos or blue jets.
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The high temperatures prevalent in the thermosphere (800–1000 K) have not been fully explained yet;Yelle (2004), pp. 15–16 existing models predict a temperature no higher than about 400 K. They may be caused by absorption of high-energy solar radiation (UV or X-ray), by heating from the charged particles precipitating from the Jovian magnetosphere, or by dissipation of upward-propagating gravity waves.Yelle (2004), pp. 22–27 The thermosphere and exosphere at the poles and at low latitudes emit X-rays, which were first observed by the Einstein Observatory in 1983.
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While primarily an astronomical research facility, the observatory also hosts two geophysics research stations, one studying the mesosphere and thermosphere, and one using lasers to probe the troposphere and stratosphere, studying aerosol and ozone content, using lidar techniques.
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Diagram showing the five primary layers of the Earth's atmosphere: exosphere, thermosphere, mesosphere, stratosphere, and troposphere. The layers are to scale. From Earth's surface to the top of the stratosphere (50 km) is just under 1% of Earth's radius.
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The circulation patterns in the upper mesosphere and thermosphere of Venus are completely different from those in the lower atmosphere. At altitudes 90–150 km the Venusian air moves from the dayside to nightside of the planet, with upwelling over sunlit hemisphere and downwelling over dark hemisphere. The downwelling over the nightside causes adiabatic heating of the air, which forms a warm layer in the nightside mesosphere at the altitudes 90–120 km. The temperature of this layer—230 K (−43 °C)—is far higher than the typical temperature found in the nightside thermosphere—100 K (−173 °C).
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Space Shuttle Endeavour to straddle the stratosphere and mesosphere in this photo. The troposphere, which contains clouds, appears orange in this photo. Diagram showing the five primary layers of the Earth's atmosphere: exosphere, thermosphere, mesosphere, stratosphere, and troposphere. The layers are to scale.
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Both modules are due for launch after 2020, on Long March 5 from Wenchang Satellite Launch Center, into low Earth orbit 340 to 450 kilometers above the Earth at an orbital inclination of 42 to 43 degrees, in the centre of the Earth's thermosphere.
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The TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics) is an orbiter mission dedicated to study the dynamics of the Mesosphere and Lower Thermosphere (MLT) portion of the Earth's atmosphere. The mission was launched from Vandenberg Air Force Base in California on December 7, 2001 aboard a Delta II rocket launch vehicle. The project is sponsored and managed by NASA, while the spacecraft was designed and assembled by the Applied Physics Laboratory at Johns Hopkins University. The mission has been extended several times, and has now collected data over an entire solar cycle, which helps in its goal to differentiate the Sun's effects on the atmosphere from other effects.
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The temperature of the troposphere decreases with height until it reaches a minimum at the tropopause, which is the boundary between the troposphere and stratosphere. On Jupiter, the tropopause is approximately 50 km above the visible clouds (or 1 bar level), where the pressure and temperature are about 0.1 bar and 110 K. In the stratosphere, the temperatures rise to about 200 K at the transition into the thermosphere, at an altitude and pressure of around 320 km and 1 μbar.Sieff et al. (1998) In the thermosphere, temperatures continue to rise, eventually reaching 1000 K at about 1000 km, where pressure is about 1 nbar.
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Radiation causes the atmosphere 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 sea level, the atmosphere turns into space, although, by the judging criteria set for the definition of the Kármán line, the thermosphere itself is part of space. The highly attenuated gas in this layer can reach during the day. Despite the high temperature, an observer or object will experience cold temperatures in the thermosphere, because the extremely low density of the gas (practically a hard vacuum) is insufficient for the molecules to conduct heat.
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DK Space Encyclopedia: Atmosphere of Venus p 58. Near the poles are anticyclonic structures called polar vortices. Each vortex is double-eyed and shows a characteristic S-shaped pattern of clouds. Above there is an intermediate layer of mesosphere which separates the troposphere from the thermosphere.
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The lower stratosphere is centered around 18 kilometers above Earth's surface. The stratosphere image is dominated by blues and greens, which indicates a cooling over time. Diagram showing the five primary layers of the Earth's atmosphere: exosphere, thermosphere, mesosphere, stratosphere, and troposphere. The layers are to scale.
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22-24 Other metal layers, e.g. iron and potassium, exist in the upper mesosphere/lower thermosphere region as well. Beginning in October 2018,The "dunes" were first spotted by photographers in Finland and Sweden. a distinct type of aurora has been identified, originating in the mesosphere.
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His stud fee in 2018 was $22,000, with two of his yearlings selling for over $200,000 in early 2019. Exosphere had a winner from his first crop when colt Thermosphere won first at Newcastle on 27 February 2020, and then the Group 3 Magic Night Stakes a fortnight later.
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One candidate for a heating mechanism is atmospheric interaction with ions in the planet's magnetic field. Other candidates are gravity waves from the interior that dissipate in the atmosphere. The thermosphere contains traces of carbon dioxide and water, which may have been deposited from external sources such as meteorites and dust.
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Scientists believe the Spot is a giant vortex similar to the Great Red Spot and also appears to be quasi-stable like the vortices in Earth's thermosphere. Interactions between charged particles generated from Io and the planet's strong magnetic field likely resulted in redistribution of heat flow, forming the Spot.
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The volume fraction of the main gases in Earth's atmosphere according to height. The heterosphere is above about 100 km in the graph. The Earth's heterosphere begins at about 100 km altitude and extends to the outer reaches of its atmosphere. It incorporates most of the thermosphere and all of the exosphere.
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QB50 is a proposed international network of 50 CubeSats for multi-point, in-situ measurements in the lower thermosphere (90–350 km) and re-entry research. QB50 is an initiative of the Von Karman Institute and is funded by the European Commission as part of the 7th Framework Programme (FP7). Double-unit (2U) CubeSats (10×10×20 cm) are developed, with one unit (the 'functional' unit) providing the usual satellite functions and the other unit (the 'science' unit) accommodating a set of standardised sensors for lower thermosphere and re-entry research. 35 CubeSats are envisaged to be provided by universities from 22 countries around the world, among them 4 are from the US, 4 from China, 4 from France, 3 from Australia and 3 from South Korea.
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The recovery phase of the ionospheric storm occurs after the negative phase ends, and neutralises the electron density. A time scale of 12 hours to 1 day can be used in accordance with the Thermosphere Ionosphere General Circulation Model (TIGCM) as a means of calculating the precise time of electron density restabilising post-storm.
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There are also high-altitude cloud bands that wrap around the planet at constant latitude. These circumferential bands have widths of 50–150 km and lie about 50–110 km above the cloud deck. These altitudes are in the layer where weather occurs, the troposphere. Weather does not occur in the higher stratosphere or thermosphere.
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The orbits of spacecraft in low Earth orbit (LEO) decay to lower and lower altitudes due to the resistance from the friction between the spacecraft's surface (i.e. , drag) and the outer layer of the Earth's atmosphere (a.k.a. the thermosphere and exosphere). Eventually, a LEO spacecraft falls out of orbit and towards the Earth's surface.
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It incorporates all of the troposphere, stratosphere, mesosphere, and the lower part of the thermosphere. Chemically the homosphere is composed of 78% nitrogen, 21% oxygen, and trace amounts of other molecules, such as argon and carbon dioxide. It contains over 99% of the mass of the Earth's atmosphere. The density of air decreases with height in the homosphere.
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The air circulated from the dayside also carries oxygen atoms, which after recombination form excited molecules of oxygen in the long-lived singlet state (1Δg), which then relax and emit infrared radiation at the wavelength 1.27 μm. This radiation from the altitude range 90–100 km is often observed from the ground and spacecraft. The nightside upper mesosphere and thermosphere of Venus is also the source of non-local thermodynamic equilibrium emissions of CO2 and nitric oxide molecules, which are responsible for the low temperature of the nightside thermosphere. The Venus Express probe has shown through stellar occultation that the atmospheric haze extends much further up on the night side than the day side. On the day side the cloud deck has a thickness of 20 km and extends up to about 65 km, whereas on the night side the cloud deck in the form of a thick haze reaches up to 90 km in altitude—well into mesosphere, continuing even further to 105 km as a more transparent haze. In 2011, the spacecraft discovered that Venus has a thin ozone layer at an altitude of 100 km. Venus has an extended ionosphere located at altitudes 120–300 km. The ionosphere almost coincides with the thermosphere.
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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 insolation received, due to the increased presence of heavier gases such as monatomic oxygen. The solar constant is thus expressed at the thermopause.
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The Uranian atmosphere can be divided into three layers: the troposphere, between altitudes of and pressures from 100 to 0.1 bar (10 MPa to 10 kPa); the stratosphere, spanning altitudes between and pressures of between (10 kPa to 10 µPa); and the thermosphere extending from 4,000 km to as high as 50,000 km from the surface. There is no mesosphere.
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Uranus's magnetotail trails behind it into space for millions of kilometres and is twisted by its sideways rotation into a long corkscrew. Uranus's magnetosphere contains charged particles: mainly protons and electrons, with a small amount of H2+ ions. Many of these particles probably derive from the thermosphere. The ion and electron energies can be as high as 4 and 1.2 megaelectronvolts, respectively.
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Atmospheric tides are global-scale periodic oscillations of the atmosphere. In many ways they are analogous to ocean tides. Atmospheric tides form an important mechanism for transporting energy input into the lower atmosphere from the upper atmosphere, while dominating the dynamics of the mesosphere and lower thermosphere. Therefore, learning about atmospheric tides is essential in understanding the atmosphere as a whole.
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During the Northern Hemisphere summer, easterly jets can form in tropical regions, typically where dry air encounters more humid air at high altitudes. Low-level jets also are typical of various regions such as the central United States. There are also jet streams in the thermosphere. Meteorologists use the location of some of the jet streams as an aid in weather forecasting.
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The atmosphere of Jupiter lacks a clear lower boundary and gradually transitions into the liquid interior of the planet. From lowest to highest, the atmospheric layers are the troposphere, stratosphere, thermosphere and exosphere. Each layer has characteristic temperature gradients. The lowest layer, the troposphere, has a complicated system of clouds and hazes, comprising layers of ammonia, ammonium hydrosulfide and water.
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Presently CIRA 1986 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.
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Ariel 3 carried five experiments. The experiments measured properties of the thermosphere as well as detected "terrestrial radio noise" from thunderstorms and measured large- scale galactic radio frequency noise. Ariel 3 was also fitted with a series of mirrors to observe the spin of the satellite. High-speed data was transmitted continuously to the Satellite Tracking and Data Acquisition Network (STADAN).
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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.
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The tides form an important mechanism for transporting energy from the lower atmosphere into the upper atmosphere, while dominating the dynamics of the mesosphere and lower thermosphere. Therefore, understanding the atmospheric tides is essential in understanding the atmosphere as a whole. Modeling and observations of atmospheric tides are needed in order to monitor and predict changes in the Earth's atmosphere (see ).
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This view from orbit shows the full moon partially obscured by Earth's atmosphere. Above the troposphere, the atmosphere is usually divided into the stratosphere, mesosphere, and thermosphere. Each layer has a different lapse rate, defining the rate of change in temperature with height. Beyond these, the exosphere thins out into the magnetosphere, where the geomagnetic fields interact with the solar wind.
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Emeritus physics professor John Harlander is part of NASA's Ionospheric Connection team, which developed instruments for a satellite mission to be launched in 2018 near the Reagan Test Site in the Pacific Ocean. Harlander teamed with his students and other scientists to design, fabricate and test an instrument that will measure winds and temperatures in the thermosphere, an upper layer of Earth's atmosphere.
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Explorer 9, known as S-56A before launch, was an American satellite which was launched in 1961 to study the density and composition of the upper thermosphere and lower exosphere. It was a reflight of the failed S-56 mission, and consisted of a , balloon which was deployed into a medium Earth orbit. The mission was conducted by NASA's Langley Research Center.
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The reason is that a vehicle at this altitude would have to travel faster than orbital velocity to derive sufficient aerodynamic lift to support itself. The line is approximately at the turbopause, above which atmospheric gases are not well-mixed. The mesopause atmospheric temperature minimum has been measured to vary from 85 to 100 km, which places the line at or near the bottom of the thermosphere.
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In the case of bodies with substantial atmospheres, such as Earth's atmosphere, the exosphere is the uppermost layer, where the atmosphere thins out and merges with interplanetary space. It is located directly above the thermosphere. Very little is known about it due to lack of research. Mercury, the Moon and three Galilean satellites of Jupiter have surface boundary exospheres, which are exospheres without a denser atmosphere underneath.
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Galileo atmospheric probe stopped transmitting at a depth of 132 km below the 1 bar "surface" of Jupiter. The atmosphere of Jupiter is classified into four layers, by increasing altitude: the troposphere, stratosphere, thermosphere and exosphere. Unlike the Earth's atmosphere, Jupiter's lacks a mesosphere. Jupiter does not have a solid surface, and the lowest atmospheric layer, the troposphere, smoothly transitions into the planet's fluid interior.
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The magnetosphere shields the surface of Earth from the charged particles of the solar wind. (image not to scale.) The troposphere, stratosphere, mesosphere, thermosphere, and exosphere are the five layers which make up Earth's atmosphere. 75% of the gases in the atmosphere are located within the troposphere, the lowest layer. In all, the atmosphere is made up of about 78.0% nitrogen, 20.9% oxygen, and 0.92% argon.
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Objects in LEO encounter atmospheric drag from gases in the thermosphere (approximately 80–500 km above the surface) or exosphere (approximately and up), depending on orbit height. Due to atmospheric drag, satellites do not usually orbit below . Objects in LEO orbit Earth between the denser part of the atmosphere and below the inner Van Allen radiation belt. Equatorial low Earth orbits (ELEO) are a subset of LEO.
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The second source of energy input into the thermosphere is solar wind 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.
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The motion of the shadow was supersonic and it generated gravity waves that were detectable as disturbances in the ionosphere. These gravity waves originate in the thermosphere at an altitude of about 180 km. Because of the obscuration of solar radiation, the ionization level dropped by 70% during the eclipse. The eclipse caused a 1–1.4 K drop in the temperature of the ionosphere.
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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 up to the thermopause at an altitude range of . The height of the thermopause varies considerably due to changes in solar activity. Because the thermopause lies at the lower boundary of the exosphere, it is also referred to as the exobase.
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Aurora australis in the Earth's atmosphere observed by Space Shuttle Discovery, May 1991 Space weather is the environmental condition within the Solar System, including the solar wind. It is studied especially surrounding the Earth, including conditions from the magnetosphere to the ionosphere and thermosphere. Space weather is distinct from terrestrial weather of the troposphere and stratosphere. The term was not used until the 1990s.
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Several other solar spacecraft would have helped with this mission, such as STEREO, Japan's Hinode, the Solar Dynamics Observatory, and ESA's Solar Orbiter. Ground-based telescopes would also assist the mission. It would have been part of a group of four missions, including the Solar Dynamics Observatory and the Geospace missions (Radiation Belt Storm Probes and Ionosphere-Thermosphere Storm Probes), from the Living With a Star program.
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Molecules on the day side are broken into their component atoms, such that normally sequestered refractory elements can exist as atomic species, including neutral and singly ionized atomic iron (Fe and Fe+) and singly ionized titanium (Ti+), only to temporarily reform once they reach the cooler night side. Thermosphere layer of KELT-9b is expected to heat up to 10000-11000 K, driven by ionization of heavy metals atoms like iron.
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The thermosphere is also characterized by strong circulation, but very different in its nature—the gases heated and partially ionized by sunlight in the sunlit hemisphere migrate to the dark hemisphere where they recombine and downwell. Unlike Earth, Venus lacks a magnetic field. Its ionosphere separates the atmosphere from outer space and the solar wind. This ionized layer excludes the solar magnetic field, giving Venus a distinct magnetic environment.
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The mesosphere has been called the "ignorosphere" because it is poorly studied relative to the stratosphere (which can be accessed with high-altitude balloons) and the thermosphere (in which satellites can orbit). A deep sodium layer is located between . Made of unbound, non-ionized atoms of sodium, the sodium layer radiates weakly to contribute to the airglow. The sodium has an average concentration of 400,000 atoms per cubic centimetre.
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The mesosphere is the third highest layer of Earth's atmosphere, occupying the region above the stratosphere and below the thermosphere. It extends from the stratopause at an altitude of about to the mesopause at above sea level. Temperatures drop with increasing altitude to the mesopause that marks the top of this middle layer of the atmosphere. It is the coldest place on Earth and has an average temperature around .
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The ionosphere () is the ionized part of Earth's upper atmosphere, from about to altitude, a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar radiation. It plays an important role in atmospheric electricity and forms the inner edge of the magnetosphere. It has practical importance because, among other functions, it influences radio propagation to distant places on the Earth.
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The stratosphere is the middle layer of the Uranian atmosphere, in which temperature generally increases with altitude from 53 K in the tropopause to between 800 and 850 K at the base thermosphere. The heating of the stratosphere is caused by the downward heat conduction from the hot thermosphere as well as by absorption of solar UV and IR radiation by methane and the complex hydrocarbons formed as a result of methane photolysis. The methane enters the stratosphere through the cold tropopause, where its mixing ratio relative to molecular hydrogen is about 3, three times below saturation. It decreases further to about 10−7 at the altitude corresponding to pressure of 0.1 mbar. Hydrocarbons heavier than methane are present in a relatively narrow layer between 160 and 320 km in altitude, corresponding to the pressure range from 10 to 0.1 mbar and temperatures from 100 to 130 K. The most abundant stratospheric hydrocarbons after methane are acetylene and ethane, with mixing ratios of around 10−7.
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The model allows to separate the contributions of both kinds of electric currents. The polar magnetic disturbances DP2 are mainly Hall currents. The auroral electrojets (DP1) with magnitudes of the order of several hundreds of kA flowing within the aurora zones consist of Hall currents and Pedersen currents. Dissipation of the Pedersen currents produces Joule heating which is transferred to the neutral gas of the thermosphere thus generating thermospheric and ionospheric disturbances.
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Increased conductivity of currents is caused by the convection electric fields of the magnetosphere that run down the lines of the magnetic field in the E-region. The increased conductivity is also from the effects of the ionospheric storm. There is also a maximisation in the E-region of the transfer of energy from plasma to neutral particles which promotes "frictional heating" and is used as a heat source for the thermosphere.
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The thermosphere gradually transitions to the exosphere. Bands of high-altitude clouds cast shadows on Neptune's lower cloud deck Models suggest that Neptune's troposphere is banded by clouds of varying compositions depending on altitude. The upper-level clouds lie at pressures below one bar, where the temperature is suitable for methane to condense. For pressures between one and five bars (100 and 500 kPa), clouds of ammonia and hydrogen sulfide are thought to form.
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The methane abundance relative to molecular hydrogen in the stratosphere is about 10−4, while the abundance ratio of other light hydrocarbons, like ethane and acetylene, to molecular hydrogen is about 10−6. Jupiter's thermosphere is located at pressures lower than 1 μbar and demonstrates such phenomena as airglow, polar aurorae and X-ray emissions.Yelle (2004), pp. 1–12 Within it lie layers of increased electron and ion density that form the ionosphere.
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The Whole Atmosphere Community Climate Model (WACCM) is used to generate computer simulations of the dynamic processes interacting between the terrestrial and solar systems that impact on Earth's climate. The original model was developed around the turn of the millennium with the most recent iteration, version 6 (WACCM6), released in 2019. The Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM-X) extends the model to space weather and space climate.
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In the stratosphere incoming solar radiation creates the ozone layer. At heights of above , in the thermosphere, the atmosphere is so thin that free electrons can exist for short periods of time before they are captured by a nearby positive ion. The number of these free electrons is sufficient to affect radio propagation. This portion of the atmosphere is partially ionized and contains a plasma which is referred to as the ionosphere.
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Auroras in sky Conditions on the Sun and in the solar wind, magnetosphere, ionosphere and thermosphere that can influence the performance and reliability of space-borne and ground-based technological systems and can endanger human life or health. Space weather can also create lot of the problems on the earth. Space weather also can create lot of auroras. But it can also disturb satellites that exchange signals from earth to space and from space to earth.
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Uranus has relatively well developed aurorae, which are seen as bright arcs around both magnetic poles. Unlike Jupiter's, Uranus's aurorae seem to be insignificant for the energy balance of the planetary thermosphere. In March 2020, NASA astronomers reported the detection of a large atmospheric magnetic bubble, also known as a plasmoid, released into outer space from the planet Uranus, after reevaluating old data recorded by the Voyager 2 space probe during a flyby of the planet in 1986.
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Temperature profile of the Uranian troposphere and lower stratosphere. Cloud and haze layers are also indicated. The Uranian atmosphere can be divided into three main layers: the troposphere, between altitudes of −300 and 50 km and pressures from 100 to 0.1 bar; the stratosphere, spanning altitudes between 50 and 4000 km and pressures between and the thermosphere/exosphere extending from 4000 km to as high as a few Uranus radii from the surface. There is no mesosphere.
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Along the last closed geomagnetic field lines with their footpoints within the auroral zones, field-aligned electric currents can flow 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 (see e.g., Magnetospheric electric convection field). 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.
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The main research activities of this department includes study on solar-terrestrial environment including solar disturbances, Earth's magnetosphere, ionosphere, thermosphere, lithosphere, atmosphere etc. Peoples also work on seismo- ionospheric precursors, lithosphere-atmosphere-ionosphere coupling processes, long-term and transient solar activity and ionospheric climatology using both ground and space based VLF receiver. Monitoring of galactic X-ray transients, Soft Gamma ray Repeaters (SGRs) and Gamma Ray Bursts (GRBs) etc. are also active research topic in this department.
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Richtersius is a monospecific genus of tardigrades in the family Richtersiidae; its sole species is Richtersius coronifer. R. coronifer is one of two species of tardigrade that have been shown to survive and continue reproducing after exposure to outer space, specifically in the thermosphere at 258–281 km above sea level with ionizing solar and galactic cosmic radiation for 10 days. However, unlike Milnesium tardigradum, R. coronifer did not survive under these conditions plus UV exposure.
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The apogee of the new craft will be approximately in the lower thermosphere, higher than the Kármán line which was SpaceShipOne's target, although the last flight of SpaceShipOne reached a one-time altitude of . SpaceShipTwo will reach , using a single hybrid rocket engine — the RocketMotorTwo. It launches from its mother ship, White Knight Two, at an altitude of , and reaches supersonic speed within 8 seconds. After 70 seconds, the rocket engine cuts out and the spacecraft will coast to its peak altitude.
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The Extreme Ultraviolet and X-ray Irradiance Sensors (EXIS) are a pair of sensors that monitor solar irradiance in the Earth's upper atmosphere. In monitoring irradiance, EXIS can detect solar flares which can disrupt power grids, communications, and navigational systems on Earth and satellites. Variability in irradiance influences conditions in the ionosphere and thermosphere. The Extreme Ultraviolet Sensor (EUVS) monitors changes in solar extreme ultraviolet irradiance which shape upper atmospheric variability, with an ultraviolet wavelength range of 5-127 nm.
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Data from EUVS can anticipate radio blackouts for high frequency (HF) communications in low latitudes and the expansion of the thermosphere, which can induce increased drag and degrade instruments on satellites in low Earth orbit. The X-Ray Sensor (XRS) component of EXIS monitors solar flares through X-ray irradiance, allowing for the prediction of a solar particle event. The XRS detects X-rays with wavelengths between 0.05-0.8 nm. Together, the EXIS instrument weighs and consumes 40 W of power.
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Uranus's atmosphere taken during the Outer Planet Atmosphere Legacy (OPAL) program. Although there is no well-defined solid surface within Uranus's interior, the outermost part of Uranus's gaseous envelope that is accessible to remote sensing is called its atmosphere. Remote-sensing capability extends down to roughly 300 km below the level, with a corresponding pressure around and temperature of . The tenuous thermosphere extends over two planetary radii from the nominal surface, which is defined to lie at a pressure of 1 bar.
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Because Neptune's atmospheric methane content is similar to that of Uranus, some unknown atmospheric constituent is thought to contribute to Neptune's colour. Neptune's atmosphere is subdivided into two main regions: the lower troposphere, where temperature decreases with altitude, and the stratosphere, where temperature increases with altitude. The boundary between the two, the tropopause, lies at a pressure of . The stratosphere then gives way to the thermosphere at a pressure lower than 10−5 to 10−4 bars (1 to 10 Pa).
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Deployment of the WSF using the Space Shuttle robotic arm Wake Shield Facility (WSF) was an experimental science platform that was placed in low Earth orbit by the Space Shuttle. It was a diameter, free-flying stainless steel disk. The WSF was deployed using the Space Shuttle's robotic arm. The WSF then used nitrogen gas thrusters to position itself about behind the Space Shuttle which was at an orbital altitude of over , within the thermosphere, where the atmosphere is exceedingly tenuous.
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The upper part of the thermosphere, where the mean free path of the molecules exceeds the scale height, is called the exosphere. The lower boundary of the Uranian exosphere, the exobase, is located at a height of about 6,500 km, or 1/4 of the planetary radius, above the surface. The exosphere is unusually extended, reaching as far as several Uranian radii from the planet. It is made mainly of hydrogen atoms and is often called the hydrogen corona of Uranus.
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Retrograde motion, or retrogression, within the Earth's atmosphere is seen in weather systems whose motion is opposite the general regional direction of airflow, i.e. from east to west against the westerlies or from west to east through the trade wind easterlies. Prograde motion with respect to planetary rotation is seen in the atmospheric super-rotation of the thermosphere of Earth and in the upper troposphere of Venus. Simulations indicate that the atmosphere of Pluto should be dominated by winds retrograde to its rotation.
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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.Schmidtke, G., Modelling of the solar radiation for aeronomical applications, in Flügge, S. (ed), Encycl. Phys. 49/7, Springer Verlag, Heidelberg, 1 During the low solar activity, about half of the total energy input into the thermosphere is thought to be solar XUV radiation.
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Figure 2. Schematic meridian-height cross-section of circulation of (a) symmetric wind component (P20), (b) of antisymmetric wind component (P10), and (d) of symmetric diurnal wind component (P11) at 3 h and 15 h local time. Upper right pannel (c) shows the horizontal wind vectors of the diurnal component in the northern hemisphere depending on local time. Within the thermosphere above about 150 km height, all atmospheric waves successively become external waves, and no significant vertical wave structure is visible.
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This instrument, which is attached to the Canadian satellite SCISAT, has shown that nitrous oxide is present throughout the entire atmosphere during all seasons, primarily due to energetic particle precipitation. Measurements taken by the instrument show that different reactions create nitrous oxide in the lower thermosphere than in the mid to upper mesosphere. The ACE-FTS is a crucial resource in predicting future ozone depletion in the upper stratosphere by comparing the different ways in which nitrous oxide is released into the atmosphere.
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The stratosphere and mesosphere extend from 65 km to 95 km in height. The thermosphere and exosphere begin at around 95 kilometres, eventually reaching the limit of the atmosphere at about 220 to 250 km. The air pressure at Venus' surface is about 92 times that of the Earth. The enormous amount of CO2 in the atmosphere creates a strong greenhouse effect, raising the surface temperature to around 470 °C, hotter than that of any other planet in the Solar System.
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The exosphere is the outermost layer of Earth's atmosphere (i.e. the upper limit of the atmosphere). It extends from the exobase, which is located at the top of the thermosphere at an altitude of about 700 km above sea level, to about 10,000 km (6,200 mi; 33,000,000 ft) where it merges into the solar wind. This layer is mainly composed of extremely low densities of hydrogen, helium and several heavier molecules including nitrogen, oxygen and carbon dioxide closer to the exobase.
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An alternative is the use of a laser beam to generate a reference light source (a laser guide star, LGS) in the atmosphere. There are two kinds of LGSs: Rayleigh guide stars and sodium guide stars. Rayleigh guide stars work by propagating a laser, usually at near ultraviolet wavelengths, and detecting the backscatter from air at altitudes between . Sodium guide stars use laser light at 589 nm to resonantly excite sodium atoms higher in the mesosphere and thermosphere, which then appear to "glow".
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The periapsis portion of the orbit would have allowed in-situ measurements of the thermosphere and lower exosphere and remote sensing of the lower atmosphere and surface. The more distant parts of the orbit would be for study of the ions and neutral gas escaping from Mars and their interactions with the solar wind. The nominal mission was planned for one martian year (approximately two Earth years). An extended mission might have allowed operation of the mission for three to five years.
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Chapman, S., and R.S. Lindzen, "Atmospheric Tides", Kluwer Dordrecht, 1970 Within the thermosphere, however, it becomes the predominant mode, reaching temperature amplitudes at the exosphere of at least 140 K and horizontal winds of the order of 100 m/s and more increasing with geomagnetic activity.Kohl, H. and J.W. King, J. Atm. Terr. Phys., 29,1045, 1967 The largest solar semidiurnal wave is mode (2, 2) with maximum pressure amplitudes near the ground of 120 hPa. It is an internal class 1 wave.
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Rays directed vertically toward the zenith are dissipated in the thermosphere, and are a significant source of heating in that layer of the upper atmosphere. At mid latitudes in typical summer conditions, rays between approximately 30 and 60 degrees from the vertical are reflected from altitudes above 125 km where the return signals are strongly attenuated first. Rays launched at shallower angles may be reflected from the upper stratosphere at approximately 45 km above the surface in mid-latitudes, or from 60–70 km in low latitudes.
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GOCE flares to magnitude +2 as the 67.5 degree solar panel briefly mirrors sunlight (3 January 2010, 17:24:23.15 UTC). GOCE's frame had fixed solar panels covering its sun-facing side, which produced 1,300 watts of power. The panels were shaped to act as fins, stabilising the spacecraft while it orbited through the residual air in the thermosphere. The ion propulsion electric engine, designed and built at QinetiQ's space centre in Farnborough, England, ejected xenon ions at velocities exceeding , which compensated for the orbital decay losses.
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Diagram showing the five primary layers of the Earth's atmosphere: exosphere, thermosphere, mesosphere, stratosphere, and troposphere. The layers are to scale. From the Earth's surface to the top of the stratosphere (50km) is just under 1% of Earth's radius. The exosphere ( "outside, external, beyond", "sphere") is a thin, atmosphere-like volume surrounding a planet or natural satellite where molecules are gravitationally bound to that body, but where the density is too low for them to behave as a gas by colliding with each other.
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The optical depth of the two upper cloud layers varies with latitude: both become thinner at the poles as compared to the equator, though in 2007 the methane cloud layer's optical depth had a local maximum at 45°S, where the southern polar collar is located (see below). The troposphere is very dynamic, exhibiting strong zonal winds, bright methane clouds, dark spots and noticeable seasonal changes. (see below) Temperature profiles in the stratosphere and thermosphere of Uranus. The shaded area is where hydrocarbons are concentrated.
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From Earth's surface to the top of the stratosphere (50 km) is just under 1% of Earth's radius. The mesosphere (; from Greek mesos, "middle") is the third layer of the atmosphere, directly above the stratosphere and directly below the thermosphere. In the mesosphere, temperature decreases as altitude increases. This characteristic is used to define its limits: it begins at the top of the stratosphere (sometimes called the stratopause), and ends at the mesopause, which is the coldest part of Earth's atmosphere with temperatures below .
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A normal thermometer 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 tides, which are driven predominantly by diurnal heating. Atmospheric waves dissipate above this level because of collisions between the neutral gas and the ionospheric plasma.
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Nitrous oxide is one of the most prominent anthropogenic ozone-depleting gases in the atmosphere. It is released into the atmosphere primarily through natural sources such as soil and rock, as well as anthropogenic process like farming. Atmospheric nitrous oxide is also created in the atmosphere as a product of a reaction between nitrogen and electronically excited ozone in the lower thermosphere. The Atmospheric Chemistry Experiment‐Fourier Transform Spectrometer (ACE-FTS) is a tool used for measuring nitrous oxide concentrations in the upper to lower troposphere.
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It has basically all the weather-associated cloud genus types generated by active wind circulation, although very tall cumulonimbus thunder clouds can penetrate the tropopause from below and rise into the lower part of the stratosphere. Most conventional aviation activity takes place in the troposphere, and it is the only layer that can be accessed by propeller-driven aircraft. orbiting in the thermosphere. Because of the angle of the photo, it appears to straddle the stratosphere and mesosphere that actually lie more than below.
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Though this reduced SOLRAD 3's data-transmission ability by half, nevertheless, the satellite still returned valuable information regarding the sun's normal levels of X-ray emissions. The SOLRAD experiment package also established that, during solar flares, the higher the energy of emitted X-rays, the more disruption caused on the Earth's thermosphere (and radio transmissions therein). The GRAB mission was also highly successful, returning so much data on Soviet air defense radar facilities that an automated analysis system had to be developed to process it all.
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Aurora australis observed from , May 1991 Space weather is a branch of space physics and aeronomy, or heliophysics, concerned with the time varying conditions within the Solar System, including the solar wind, emphasizing the space surrounding the Earth, including conditions in the magnetosphere, ionosphere, thermosphere, and exosphere. Space weather is distinct from but conceptually related to the terrestrial weather of the atmosphere of Earth (troposphere and stratosphere). The term space weather was first used in the 1950s and came into common usage in the 1990s.
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The Student Nitric Oxide Explorer (SNOE), also known as Explorer 72 and STEDI 1, was a small scientific satellite which studied the concentration of nitric oxide in the thermosphere. It was launched in 1998 as part of NASA's Explorers program. The satellite was the first of three missions developed within the Student Explorer Demonstration Initiative (STEDI) funded by NASA. The satellite was developed by the University of Colorado Boulder Laboratory for Atmospheric and Space Physics (LASP) and had met its goals by the time its mission ended with reentry on December 13, 2003.
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The purpose of the Explorer 51 mission was to investigate the thermosphere, with emphasis on the energy transfer and processes that govern its state. The study of photochemical processes accompanying the absorption of solar UV radiation in the earth's atmosphere was accomplished by making closely coordinated measurements of reacting constituents and the solar input. The data from Explorer 51 served, among other things, to obtain the angular load distribution around the satellite and compare it with the data of Explorer 31 and model the hydroxyl ion emissions in the Earth's atmosphere.
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The relatively recent creation of miniaturized silicon drift detectors has enabled the MinXSS measurements. MinXSS data will provide a means of probing the solar corona—especially in active regions and solar flares—and will be used as an input for models of the Earth's upper atmosphere, particularly the ionosphere, thermosphere, and mesosphere. 550x550px MinXSS is also the first flight of the Blue Canyon Technologies XACT attitude determination and control system (ADCS), one of the only commercially available 3-axis ADCSs for CubeSats. It is performing even better than its specification.
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Turbulence at Triton's surface creates a troposphere (a "weather region") rising to an altitude of 8 km. Streaks on Triton's surface left by geyser plumes suggest that the troposphere is driven by seasonal winds capable of moving material of over a micrometre in size. Unlike other atmospheres, Triton's lacks a stratosphere, and instead has a thermosphere from altitudes of 8 to 950 km, and an exosphere above that. The temperature of Triton's upper atmosphere, at , is higher than that at its surface, due to heat absorbed from solar radiation and Neptune's magnetosphere.
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Neptune's spectra suggest that its lower stratosphere is hazy due to condensation of products of ultraviolet photolysis of methane, such as ethane and ethyne. The stratosphere is also home to trace amounts of carbon monoxide and hydrogen cyanide. The stratosphere of Neptune is warmer than that of Uranus due to the elevated concentration of hydrocarbons. For reasons that remain obscure, the planet's thermosphere is at an anomalously high temperature of about 750 K. The planet is too far from the Sun for this heat to be generated by ultraviolet radiation.
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The thermosphere in this range has large gradients of pressure, temperature and composition, and varies greatly due to space weather. The temperature of outer space is measured in terms of the kinetic activity of the gas, as it is on Earth. The radiation of outer space has a different temperature than the kinetic temperature of the gas, meaning that the gas and radiation are not in thermodynamic equilibrium. All of the observable universe is filled with photons that were created during the Big Bang, which is known as the cosmic microwave background radiation (CMB).
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Solar tides will refer to only thermal solar tides from this point. Solar energy is absorbed throughout the atmosphere some of the most significant in this context are water vapor at (≈0-15 km) in the troposphere, ozone at (≈30 to 60 km) in the stratosphere and molecular oxygen and molecular nitrogen at (≈120 to 170 km) in the thermosphere. Variations in the global distribution and density of these species result in changes in the amplitude of the solar tides. The tides are also affected by the environment through which they travel.
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The thermosphere and upper part of the stratosphere contain a large concentration of ions and electrons, forming the ionosphere of Uranus. Radio occultation observations by the Voyager 2 spacecraft showed that the ionosphere lies between 1,000 and 10,000 km altitude and may include several narrow and dense layers between 1,000 and 3,500 km. The electron density in the Uranian ionosphere is on average , reaching to as high as in the narrow layers in the stratosphere. The ionosphere is mainly sustained by solar UV radiation and its density depends on the solar activity.
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The auroral activity on Uranus is not as powerful as at Jupiter and Saturn and contributes little to the ionization. The high electron density may be in part caused by the low concentration of hydrocarbons in the stratosphere. One of the sources of information about the ionosphere and thermosphere comes from ground-based measurements of the intense mid-infrared (3–4 μm) emissions of the trihydrogen cation (). The total emitted power is 1–2 W—an order of magnitude higher than that the near-infrared hydrogen quadrupole emissions.
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The high temperature and relatively high pressure at the base of the thermosphere explain in part why Uranus's exosphere is so vast. The number density of atomic hydrogen in the corona falls slowly with the distance from the planet, remaining as high a few hundred atoms per cm3 at a few radii from Uranus. The effects of this bloated exosphere include a drag on small particles orbiting Uranus, causing a general depletion of dust in the Uranian rings. The infalling dust in turn contaminates the upper atmosphere of the planet.
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Satellites can not measure each height of the atmosphere separately, but instead measure a set of bands that slightly overlap. The overlap between the cooling stratosphere in the measurements of tropospheric warming may cause the latter to be underestimated slightly. The heated atmosphere contains more water vapour, which is itselfs also a greenhouse gas and acts as an self- reinforcing feedback. 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.
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Going upwards from the ground, these are the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. The density of air is mainly determined by temperature and water vapor content, the density of sea water by temperature and salinity, and the density of lake water by temperature. Where stratification occurs, there may be thin layers in which temperature or some other property changes more rapidly with height or depth than the surrounding fluid. Depending on the main sources of buoyancy, this layer may be called a pycnocline (density), thermocline (temperature), halocline (salinity), or chemocline (chemistry, including oxygenation).
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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 layers 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,Willson, R.C., Measurements of the solar total irradiance and its variability, Space Sci. Rev., 38, 203, 1984 the solar XUV radiation is highly variable in time and space.
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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 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.
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An aurora (plural: auroras or aurorae), sometimes referred to as polar lights (aurora polaris), northern lights (aurora borealis), or southern lights (aurora australis), is a natural light display in the Earth's sky, predominantly seen in high-latitude regions (around the Arctic and Antarctic). Auroras are the result of disturbances in the magnetosphere caused by solar wind. These disturbances are sometimes strong enough to alter the trajectories of charged particles in both solar wind and magnetospheric plasma. These particles, mainly electrons and protons, precipitate into the upper atmosphere (thermosphere/exosphere).
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Saturn and its northern auroras (composite image). Unlike Jupiter's, the Saturn's main auroral ovals are not related to the breakdown of the co–rotation of the plasma in the outer parts of the planet's magnetosphere. The aurorae on Saturn are thought to be connected to the reconnection of the magnetic field under the influence of the Solar wind (Dungey cycle), which drives an upward current (about 10 million amperes) from the ionosphere and leads to the acceleration and precipitation of energetic (1–10 keV) electrons into the polar thermosphere of Saturn.
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Atmospheric super-rotation is the state where a planet's atmosphere rotates faster than the planet itself. The atmosphere of Venus is one example of extreme super-rotation; the Venusian atmosphere circles the planet in just four Earth days, much faster than Venus' sidereal day of 243 Earth days. Atmospheric super-rotation has also been observed on Titan, the largest moon of Saturn. It is believed that the Earth's thermosphere has a small net super- rotation in excess of the surface rotational velocity, although estimates of the size of the phenomenon vary widely.
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The stratosphere, extending from the top of the troposphere to the bottom of the mesosphere, contains the ozone layer. The ozone layer ranges in altitude between 15 and 35 km, and is where most of the ultraviolet radiation from the Sun is absorbed. The top of the mesosphere, ranges from 50 to 85 km, and is the layer wherein most meteors burn up. The thermosphere extends from 85 km to the base of the exosphere at 400 km and contains the ionosphere, a region where the atmosphere is ionized by incoming solar radiation.
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The ionosphere increases in thickness and moves closer to the Earth during daylight and rises at night allowing certain frequencies of radio communication over a greater range. The Kármán line, located within the thermosphere at an altitude of 100 km, is commonly used to define the boundary between Earth's atmosphere and outer space. The exosphere begins variously from about 690 to 1,000 km above the surface, where it interacts with the planet's magnetosphere. Each of the layers has a different lapse rate, defining the rate of change in temperature with height.
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The Earth's atmospheric pressure drops to about at of altitude, the Kármán line, which is a common definition of the boundary with outer space. Beyond this line, isotropic gas pressure rapidly becomes insignificant when compared to radiation pressure from the Sun and the dynamic pressure of the solar winds, so the definition of pressure becomes difficult to interpret. The thermosphere in this range has large gradients of pressure, temperature and composition, and varies greatly due to space weather. Astrophysicists prefer to use number density to describe these environments, in units of particles per cubic centimetre.
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The main objective of the space weather segment (SWE) is to detect and forecast of space weather events, avoid adverse effect on European space assets and ground-based infrastructure. To achieve that, the segment will focus on delivery of real-time space weather information, forecasts and warnings, supported by a data archive, applications and services. Assets currently available for the segment consist of multiple ground-based and spaceborne sensors monitoring the Sun, solar wind and Earth's magnetosphere, ionosphere and thermosphere. These include the PROBA2 satellite and the Kanzelhoehe Solar Observatory.
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His award winning mystery novel, The Thermosphere Murders, is about two American astronauts' murder cases and the abnormal explosion of a Russian spacecraft returning from the imaginary space station, "The Universal Space Station". This unique new type of mystery was selected to be one of the top 3 finalists in "The 4th Soji Shimada Mystery Awards" and is currently in circulation at the San Francisco Public Library. Lin became a full time novelist after receiving the mystery award, his 2016 novel, The Palace of Firebirds, is published by Showwe. It is a mystery and a love story spanning half a century.
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The Kármán line lies within the lower thermosphere (not to scale)Layers of the Atmosphere, National Weather Service JetStream – Online School for Weather The Kármán line is an attempt to define a boundary between Earth's atmosphere and outer space. This is important for legal and regulatory measures; aircraft and spacecraft fall under different jurisdictions and are subject to different treaties. The Fédération Aéronautique Internationale (FAI), an international standard-setting and record-keeping body for aeronautics and astronautics, defines the Kármán line as the altitude of above Earth's mean sea level. Other organizations do not use this definition.
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Alan Eustace set the current world record for highest and longest-distance free fall jump in 2014 when he jumped from . However, Joseph Kittinger still holds the record for longest-duration free fall, at 4 minutes and 36 seconds, which he accomplished during his 1960 jump from . Higher jumps from the mesosphere or thermosphere have yet to be successfully performed, though Orbital Outfitters,Orbital Outfitters now defunct, was working to create a suit that would have enabled safe space diving. Space diving from beyond the stratosphere was first imagined in 1934, appearing in E. E. "Doc" Smith's science fiction novel Triplanetary.
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MW 18014 was part of a series of vertical test launches made in June 1944 designed to gauge the rocket's behaviour in vacuum. MW 18014 broke the altitude record set by one of its predecessors (launched on 3 October 1942 English translation 1954.) to attain an apogee of 176 km. MW 18014 was the first man-made object to cross into outer space, as defined by the 100 km Kármán Line. This particular altitude was not considered significant at the time; the Peenemünde rocket scientists rather celebrated the V-4 launch in October 1942, first to reach the thermosphere.
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GOLD is intended to perform a two-year mission imaging Earth's thermosphere and ionosphere from geostationary orbit. GOLD is a two- channel far-ultraviolet (FUV) imaging spectrograph built by the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder and flown as a hosted payload on the commercial communications satellite SES-14. Additional organizations participating in the GOLD mission include the National Center for Atmospheric Research, Virginia Tech, the University of California Berkeley, the University of Central Florida, Computational Physics Inc., the National Oceanic and Atmospheric Administration, the U.S. Naval Research Laboratory, Boston University, and Clemson University.
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Solar Dynamics Observatory spacecraft Van Allen Probes logo The first two science missions have launched: Solar Dynamics Observatory (SDO) and Van Allen Probes. The SDO mission launched on February 11, 2010, and the Van Allen Probes mission launched on August 30, 2012. Mission have included Balloon Array for Radiation-belt Relativistic Electron Losses (BARREL), Space Environment Testbeds (SET), Space Environment Testbeds, the Solar Orbiter Collaboration (SOC), and Parker Solar Probe (PSP).Living With a Star Program Missions Science requirements and conceptual mission implementation have been defined for the Ionosphere-Thermosphere Storm Probes (ITSP) and the Solar Sentinels.
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The mesosphere of Venus extends from 65 km to 120 km in height, and the thermosphere begins at approximately 120 km, eventually reaching the upper limit of the atmosphere (exosphere) at about 220 to 350 km. The exosphere begins when the atmosphere becomes so thin that the average number of collisions per air molecule is less than one. The mesosphere of Venus can be divided into two layers: the lower one between 62–73 kmThis thickness corresponds to the polar latitudes. It is narrower near the equator—65–67 km. and the upper one between 73–95 km.
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The ratio N2/O which is a measure of the electron density at the ionospheric F region is highly affected by these variations.Prölss, G.W., and M. K. Bird, "Physics of the Earth's Space Environment", Springer Verlag, Heidelberg, 2010 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 10-km thick band that occurs at the edge of the mesosphere, 80 to 100 km above Earth's surface. The sodium has an average concentration of 400,000 atoms per cubic centimeter.
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It has since increased in intensity and changed color from white to red. In April 2017, scientists reported the discovery of a "Great Cold Spot" in Jupiter's thermosphere at its north pole that is across, wide, and cooler than surrounding material. The feature was discovered by researchers at the Very Large Telescope in Chile, who then searched archived data from the NASA Infrared Telescope Facility between 1995 and 2000. They found that, while the Spot changes size, shape and intensity over the short term, it has maintained its general position in the atmosphere across more than 15 years of available data.
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X-ray emission is expected from astronomical objects that contain extremely hot gases at temperatures from about a million kelvin (K) to hundreds of millions of kelvin (MK). Moreover, the maintenance of the E-layer of ionized gas high in the Earth's thermosphere also suggested a strong extraterrestrial source of X-rays. Although theory predicted that the Sun and the stars would be prominent X-ray sources, there was no way to verify this because Earth's atmosphere blocks most extraterrestrial X-rays. It was not until ways of sending instrument packages to high altitude were developed that these X-ray sources could be studied.
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The largest-amplitude atmospheric tides are mostly generated in the troposphere and stratosphere when the atmosphere is periodically heated, as water vapor and ozone absorb solar radiation during the day. These tides propagate away from the source regions and ascend into the mesosphere and thermosphere. Atmospheric tides can be measured as regular fluctuations in wind, temperature, density and pressure. Although atmospheric tides share much in common with ocean tides they have two key distinguishing features: # Atmospheric tides are primarily excited by the Sun's heating of the atmosphere whereas ocean tides are excited by the Moon's gravitational pull and to a lesser extent by the Sun's gravity.
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SvalSat is part of NASA's Near Earth Network. This includes support for the Earth Observing System, which includes satellites such as Aqua, Aura, Ice, Cloud and Land Elevation Satellite, and QuikSCAT, as well as the Small Explorer program which includes Galaxy Evolution Explorer, the Submillimeter Wave Astronomy Satellite, Swift Gamma-Ray Burst Mission, Thermosphere Ionosphere Mesosphere Energetics and Dynamics, Interface Region Imaging Spectrograph, and Transition Region and Coronal Explorer. SvalSat and Poker Flat are collectively responsible for half of the network's 140 daily passes. Satellites operated by the National Oceanic and Atmospheric Administration using SvalSat includes the Suomi National Polar-Orbiting Partnership and the Defense Meteorological Satellite Program.
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The speed of sound (blue) depends only on the temperature variation at altitude (red) and can be calculated from it since isolated density and pressure effects on the speed of sound cancel each other. The speed of sound increases with height in two regions of the stratosphere and thermosphere, due to heating effects in these regions. Mach number is a measure of the compressibility characteristics of fluid flow: the fluid (air) behaves under the influence of compressibility in a similar manner at a given Mach number, regardless of other variables. As modeled in the International Standard Atmosphere, dry air at mean sea level, standard temperature of , the speed of sound is .
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In the late 1990s and early 2000s, a series of journal papers and government reports described common modeling infrastructure as necessary to the competitiveness and evolution of the U.S. Earth science modeling community. These reports resulted in a number of new community projects. The Earth System Modeling Framework (ESMF) and the Earth System Modeling (ESM) are two of the largest modeling approaches. Similar projects were initiated in related domains, including the Space Weather Modeling Framework (SWMF/CESM), to study conditions including the Sun, solar wind, magnetosphere, ionosphere, and thermosphere that potentially can influence performance and reliability of space-borne and ground-based technological systems or can endanger human life or health.
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Far away in the Central Asian steppes a test site is hidden where new jet aircraft are being tested, including an experimental aircraft with a rocket engine on atomic radioactive accelerators, deployed from under the wing of a carrier aircraft and capable of making a suborbital manned space flight - to reach a thermosphere altitude of 100 km, as well as speeds over 7,200 km / h. The pilot-engineer Sergei Fyodorovich Baikalov and the research officer Vera Borisovna Stankevich are sent to this range. During the flight, the first tester of the "Cyclone" is Kazantsev. It is necessary to understand the cause of the disaster in order to prevent its recurrence.
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An aurora is a natural light display in the sky, especially in the high latitude (Arctic and Antarctic) regions, in the form of a large circle around the pole. It is caused by the collision of solar wind and charged magnetospheric particles with the high altitude atmosphere (thermosphere). Most auroras occur in a band known as the auroral zone, which is typically 3° to 6° wide in latitude and observed at 10° to 20° from the geomagnetic poles at all longitudes, but often most vividly around the spring and autumn equinoxes. The charged particles and solar wind are directed into the atmosphere by the Earth's magnetosphere.
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TIMED Mission diagram (NASA) The Mesosphere and Lower Thermosphere (MLT) region of the atmosphere to be studied by TIMED is located between 60 and 180 km 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 during the peak of the Sun's 11-year solar cycle when the greatest amounts of its energy are being released. Understanding these interactions is also important for our understanding of various subjects in geophysics, meteorology, and atmospheric science, as solar radiation is one of the primary driving forces behind atmospheric tides. Changes in the MLT can also affect modern satellite and radio telecommunications.
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The exact upper and lower boundaries of the mesosphere vary with latitude and with season (higher in winter and at the tropics, lower in summer and at the poles), but the lower boundary is usually located at altitudes from above the Earth's surface and the upper boundary (the mesopause) is usually around . The stratosphere and the mesosphere are sometimes collectively referred to as the "middle atmosphere", which spans altitudes approximately between 12 and 80 km above Earth's surface. The mesopause, at an altitude of , separates the mesosphere from the thermosphere—the second-outermost layer of Earth's atmosphere. This is the turbopause, below which different chemical species are well-mixed due to turbulent eddies.
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The atmospheric wave modes degenerate to the spherical functions Pnm with m a meridional wave number and n the zonal wave number (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:Köhnlein, W., A model of thermospheric temperature and composition, Planet.
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In the stratosphere, starting above about 20 km, the temperature increases with height, due to heating within the ozone layer caused by capture of significant ultraviolet radiation from the Sun by the dioxygen and ozone gas in this region. Still another region of increasing temperature with altitude occurs at very high altitudes, in the aptly-named thermosphere above 90 km. Because in an ideal gas of constant composition the speed of sound depends only on temperature and not on the gas pressure or density, the speed of sound in the atmosphere with altitude takes on the form of the complicated temperature profile (see illustration to the right), and does not mirror altitudinal changes in density or pressure.
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Ayaks was initially a classified Soviet spaceplane project aimed to design a new kind of global range hypersonic cruise vehicle capable of flying and conducting a variety of military missions in the mesosphere. The original concept revolved around a hypersonic reconnaissance aircraft project, but later was expanded into the wider concept of hypersonic multi-purpose military and civilian jets, as well as a SSTO platform for launching satellites. The mesosphere is the layer of the Earth's atmosphere from to high, above the stratosphere and below the thermosphere. It is very difficult to fly in the mesosphere — the air is too rarefied for aircraft wings to generate lift, but sufficiently dense to cause aerodynamic drag on satellites.
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The ISS is maintained in a nearly circular orbit with a minimum mean altitude of and a maximum of , in the centre of the thermosphere, at an inclination of 51.6 degrees to Earth's equator. This orbit was selected because it is the lowest inclination that can be directly reached by Russian Soyuz and Progress spacecraft launched from Baikonur Cosmodrome at 46° N latitude without overflying China or dropping spent rocket stages in inhabited areas. It travels at an average speed of , and completes orbits per day (93 minutes per orbit). The station's altitude was allowed to fall around the time of each NASA shuttle flight to permit heavier loads to be transferred to the station.
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The F region of the ionosphere is home to the F layer of ionization, also called the Appleton–Barnett layer, after the English physicist Edward Appleton and New Zealand physicist and meteorologist Miles Barnett. As with other ionospheric sectors, 'layer' implies a concentration of plasma (physics), while 'region' is the volume that contains the said layer. The F region contains ionized gases at a height of around 150–800 km (100 to 500 miles) above sea level, placing it in the Earth's thermosphere, a hot region in the upper atmosphere, and also in the heterosphere, where chemical composition varies with height. Generally speaking, the F region has the highest concentration of free electrons and ions anywhere in the atmosphere.
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Atmosphere of WASP-33b was detected by monitoring light as the planet passed behind its star (top)—higher temperatures result in the low stratosphere due to molecules absorbing radiation from the star (right)—lower temperatures at higher altitudes would result if there were no stratosphere (left) In 2020, with the detection of secondary eclipses (when the planet is blocked by its star), the mass of planet along with temperature profile across its surface was measured. The WASP-33b have a strong winds in its atmosphere similar to Venus, shifting hottest spot 28.7±7.1 degrees to the west. The averaged wind speed is 8.5 km/s in the thermosphere. The illuminated side brightness temperature is 3014±60 K, while nightside brightness temperature is 1605±45 K.
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EKWB Universal GPU blocks, marketed as EK-VGA Supremacy for single graphics card setup, and a larger version called EK-Thermosphere, designed for use with more than one graphics card. These blocks only cool the GPU core, and so leave the VRAM and VRMs on a card to be cooled by air, usually. Should a user fail to ensure these vital parts of the card are also cooled, either by placing a fan to direct air over them, or by the use of stick on heat sinks, it's possible for the card to shutdown, or die even, from overheating. Just like the CPU blocks, they offer the blocks in different style offerings in both bare copper and nickel plating, and cover plates made from Acetal or Plexi.
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Moreover, because electro-magnetic interference generated by the spacecraft prevented ground controllers from requesting data from both spacecraft at the same time, SOLRAD 3/GRAB 2's transmissions were limited to odd-numbered days, INJUN's to even-numbered days; thus, data was only recovered for half of each satellite's lifetime. Nevertheless, the SOLRAD package on the satellite made several important findings. It established the Sun's normal X-ray radiation levels during times of inactivity at levels below 14Å in wavelength (less than 5×10−3 ergs/cm2/sec). The satellite also found that the higher the hardness (energy level) of X-rays emitted during solar flares, the greater the disturbances and microwave bursts in the thermosphere, both affecting radio communications.
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Microbaroms that propagate up to the lower thermosphere may be carried in an atmospheric waveguide, refracted back toward the surface from below 120 km and above 150 km altitudes, or dissipated at altitudes between 110 and 140 km. They may also be trapped near the surface in the lower troposphere by planetary boundary layer effects and surface winds, or they may be ducted in the stratosphere by upper-level winds and returned to the surface through refraction, diffraction or scattering. These tropospheric and stratospheric ducts are only generated along the dominant wind directions, may vary by time of day and season, and will not return the sound rays to the ground when the upper winds are light. The angle of incidence of the microbarom ray determines which of these propagation modes it experiences.
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By combining the gravity data with information about sea surface height gathered by other satellite altimeters, scientists were able to track the direction and speed of geostrophic ocean currents. The low orbit and high accuracy of the system greatly improved the known accuracy and spatial resolution of the geoid (the theoretical surface of equal gravitational potential on the Earth). The satellite's unique arrow shape and fins helped keep GOCE stable as it flew through the thermosphere at a comparatively low altitude of . Additionally, an ion propulsion system continuously compensated for the variable deceleration due to air drag without the vibration of a conventional chemically powered rocket engine, thus limiting the errors in gravity gradient measurements caused by non-gravitational forces and restoring the path of the craft as closely as possible to a purely inertial trajectory.
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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 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.
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The favorable location of Millstone Hill at sub-auroral latitudes combined with the great operational range afforded by the steerable antenna permit observations over a latitude span encompassing the region between the polar cap and the near-equatorial ionosphere. Since 1982 the Haystack Observatory Atmospheric Sciences Group has been supported for operating the Millstone Hill research radar as a part of the incoherent scatter radar chain and for associated studies of the auroral and sub-auroral ionosphere and thermosphere. The meridional radar chain extends from Sondrestrom Upper Atmospheric Research Facility in Kangerlussuaq, Greenland through Millstone Hill at mid-latitudes, beyond Arecibo at low latitudes, to the Jicamarca facility at the magnetic equator in Peru. The radar chain forms an integral part of the NSF-supported CEDAR (Coupling, Energetics, and Dynamics of Atmospheric Regions) observing network and Millstone Hill observations and analysis have contributed extensively to the successes of the CEDAR initiative.
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1. The scale height sh is defined as , where is the gas constant, is the average molar mass in the Jovian atmosphere, T is temperature and is the gravitational acceleration at the surface of Jupiter. As the temperature varies from 110 K in the tropopause up to 1000 K in the thermosphere, the scale height can assume values from 15 to 150 km. 2. The Galileo atmospheric probe failed to measure the deep abundance of oxygen, because the water concentration continued to increase down to the pressure level of 22 bar, when it ceased operating. While the actually measured oxygen abundances are much lower than the solar value, the observed rapid increase of water content of the atmosphere with depth makes it highly likely that the deep abundance of oxygen indeed exceeds the solar value by a factor of about 3—much like other elements. 3.
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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 coldest region on Earth with temperatures as low as -100 °C (-148 °F or 173 K).International Union of Pure and Applied Chemistry. "mesosphere". Compendium of Chemical Terminology Internet edition The altitude of the mesopause for many years was assumed to be at around 85 km (53 mi.), but observations to higher altitudes and modeling studies in the last 10 years have shown that in fact the mesopause consists of two minima - one at about 85 km and a stronger minimum at about 100 km (62 mi). Another feature is that the summer mesopause is cooler than the winter (sometimes referred to as the mesopause anomaly).
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The largest-amplitude atmospheric tides are mostly generated in the troposphere and stratosphere when the atmosphere is periodically heated as water vapour and ozone absorb solar radiation during the day. The tides generated are then able to propagate away from these source regions and ascend into the mesosphere and thermosphere. Atmospheric tides can be measured as regular fluctuations in wind, temperature, density and pressure. Although atmospheric tides share much in common with ocean tides they have two key distinguishing features: i) Atmospheric tides are primarily excited by the Sun's heating of the atmosphere whereas ocean tides are primarily excited by the Moon's gravitational field. This means that most atmospheric tides have periods of oscillation related to the 24-hour length of the solar day whereas ocean tides have longer periods of oscillation related to the lunar day (time between successive lunar transits) of about 24 hours 51 minutes.
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The CSS will be operated in Low Earth Orbit, 340 to 450 kilometers above the Earth at an orbital inclination of 42 to 43 degrees, in the centre of the Earth's thermosphere. At this altitude there is a variety of space debris, consisting of many different objects including entire spent rocket stages, dead satellites, explosion fragments—including materials from anti-satellite weapon tests (such as the 2007 Chinese anti-satellite missile test, the 2019 Indian anti-satellite test and the 1985 U.S. ASM-135 ASAT anti-satellite test), paint flakes, slag from solid rocket motors, coolant released by RORSAT nuclear powered satellites and some clumps remaining from the 750,000,000 small needles from the American military Project West Ford. These objects, in addition to natural micrometeoroids, are a significant threat. Large objects could destroy the station, but are less of a threat as their orbits can be predicted.
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It is convenient to separate the atmospheric regions according to the two temperature minima at about 12 km altitude (the tropopause) and at about 85 km (the mesopause) (Figure 1). The thermosphere (or the upper atmosphere) is the height region above 85 km, while the region between the tropopause and the mesopause is the middle atmosphere (stratosphere and mesosphere) where absorption of solar UV radiation generates the temperature maximum near 45 km altitude and causes the ozone layer. Figure 1. Nomenclature of atmospheric regions based on the profiles of electric conductivity (left), temperature (middle), and electron number density in m−3(right) 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).
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As an Earth-grazer passes through the atmosphere its mass and velocity are changed, so that its orbit, as it re-enters space, will be different from its orbit as it encountered Earth's atmosphere.US19720810 (Daylight Earth grazer) Global Superbolic Network Archive, 2000, 'Size: 5 to 10 m'Daylight Fireball of August 10, 1972 C. Kronberg, Munich Astro Archive, archived summary by Gary W. Kronk of early analysis and of Zdeněk Ceplecha's paper for Astronomy and Astrophysics in 1994, '3 meters, if a carbonaceous chondrite, or as large as 14 meters, if composed of cometary materials', 'post-encounter ... 2 or 10 meters' There is no agreed-upon end to the upper atmosphere, but rather incrementally thinner air from the stratosphere (~50 km), mesosphere (~85 km), and thermosphere (~690 km) up to the exosphere (~10,000) (see also thermopause). For example, a meteoroid can become a meteor at an altitude of 85–120 km above the Earth.
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The U.S. Air Force definition of an astronaut is a person who has flown higher than above mean sea level, approximately the line between the mesosphere and the thermosphere. NASA formerly used the FAI's figure, though this was changed in 2005, to eliminate any inconsistency between military personnel and civilians flying in the same vehicle, when three veteran NASA X-15 pilots (John B. McKay, William H. Dana and Joseph Albert Walker) were retroactively (two posthumously) awarded their astronaut wings, as they had flown between and in the 1960s, but at the time had not been recognized as astronauts. The latter altitude, achieved twice by Walker, exceeds the modern international definition of the boundary of space. Recent works by Jonathan McDowell (Harvard-Smithsonian Center for Astrophysics) and Thomas Gangale (University of Nebraska-Lincoln) advocate that the demarcation of space should be at , citing as evidence von Kármán's original notes and calculations (which concluded the boundary should be 270,000 ft), plus functional, cultural, physical, technological, mathematical, and historical factors.
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