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Scale Height
In atmospheric, earth, and planetary sciences, a scale height, usually denoted by the capital letter ''H'', is a distance ( vertical or radial) over which a physical quantity decreases by a factor of e (the base of natural logarithms, approximately 2.718). Scale height used in a simple atmospheric pressure model For planetary atmospheres, scale height is the increase in altitude for which the atmospheric pressure decreases by a factor of ''e''. The scale height remains constant for a particular temperature. It can be calculated by H = \frac, or equivalently, H = \frac, where : ''k''B = Boltzmann constant = : ''R'' = molar gas constant = 8.31446 J⋅K−1⋅mol−1 : ''T'' = mean atmospheric temperature in kelvins = 250 K for Earth : ''m'' = mean mass of a molecule : ''M'' = mean molar mass of atmospheric particles = 0.029 kg/mol for Earth : ''g'' = acceleration due to gravity at the current location The pressure (force per unit area) at a given altitu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pressure Air
Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and even by industry. Further, both spellings are often used ''within'' a particular industry or country. Industries in British English-speaking countries typically use the "gauge" spelling. is the pressure relative to the ambient pressure. Various units are used to express pressure. Some of these derive from a unit of force divided by a unit of area; the SI unit of pressure, the pascal (Pa), for example, is one newton per square metre (N/m2); similarly, the pound-force per square inch (psi, symbol lbf/in2) is the traditional unit of pressure in the imperial and US customary systems. Pressure may also be expressed in terms of standard atmospheric pressure; the unit atmosphere (atm) is equal to this pressure, and the torr is defined as of thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acceleration
In mechanics, acceleration is the Rate (mathematics), rate of change of the velocity of an object with respect to time. Acceleration is one of several components of kinematics, the study of motion. Accelerations are Euclidean vector, vector quantities (in that they have Magnitude (mathematics), magnitude and Direction (geometry), direction). The orientation of an object's acceleration is given by the orientation of the ''net'' force acting on that object. The magnitude of an object's acceleration, as described by Newton's second law, is the combined effect of two causes: * the net balance of all external forces acting onto that object — magnitude is Direct proportionality, directly proportional to this net resulting force; * that object's mass, depending on the materials out of which it is made — magnitude is Inverse proportionality, inversely proportional to the object's mass. The International System of Units, SI unit for acceleration is metre per second squared (, \ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jupiter
Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined and slightly less than one-thousandth the mass of the Sun. Its diameter is 11 times that of Earth and a tenth that of the Sun. Jupiter orbits the Sun at a distance of , with an orbital period of . It is the List of brightest natural objects in the sky, third-brightest natural object in the Earth's night sky, after the Moon and Venus, and has been observed since prehistoric times. Its name derives from that of Jupiter (god), Jupiter, the chief deity of ancient Roman religion. Jupiter was the first of the Sun's planets to form, and its inward migration during the primordial phase of the Solar System affected much of the formation history of the other planets. Jupiter's atmosphere consists of 76% hydrogen and 24% helium by mass, with a denser ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mars
Mars is the fourth planet from the Sun. It is also known as the "Red Planet", because of its orange-red appearance. Mars is a desert-like rocky planet with a tenuous carbon dioxide () atmosphere. At the average surface level the atmospheric pressure is a few thousandths of Earth's, atmospheric temperature ranges from and cosmic radiation is high. Mars retains some water, in the ground as well as thinly in the atmosphere, forming cirrus clouds, frost, larger polar regions of permafrost and ice caps (with seasonal snow), but no liquid surface water. Its surface gravity is roughly a third of Earth's or double that of the Moon. It is half as wide as Earth or twice the Moon, with a diameter of , and has a surface area the size of all the dry land of Earth. Fine dust is prevalent across the surface and the atmosphere, being picked up and spread at the low Martian gravity even by the weak wind of the tenuous atmosphere. The terrain of Mars roughly follows a north-south ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth
Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all of Earth's water is contained in its global ocean, covering Water distribution on Earth, 70.8% of Earth's crust. The remaining 29.2% of Earth's crust is land, most of which is located in the form of continental landmasses within Earth's land hemisphere. Most of Earth's land is at least somewhat humid and covered by vegetation, while large Ice sheet, sheets of ice at Polar regions of Earth, Earth's polar polar desert, deserts retain more water than Earth's groundwater, lakes, rivers, and Water vapor#In Earth's atmosphere, atmospheric water combined. Earth's crust consists of slowly moving tectonic plates, which interact to produce mountain ranges, volcanoes, and earthquakes. Earth's outer core, Earth has a liquid outer core that generates a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States's civil list of government space agencies, space program, aeronautics research and outer space, space research. National Aeronautics and Space Act, Established in 1958, it succeeded the National Advisory Committee for Aeronautics (NACA) to give the American space development effort a distinct civilian orientation, emphasizing peaceful applications in space science. It has since led most of America's space exploration programs, including Project Mercury, Project Gemini, the 1968–1972 Apollo program missions, the Skylab space station, and the Space Shuttle. Currently, NASA supports the International Space Station (ISS) along with the Commercial Crew Program and oversees the development of the Orion (spacecraft), Orion spacecraft and the Sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Venus
Venus is the second planet from the Sun. It is often called Earth's "twin" or "sister" planet for having almost the same size and mass, and the closest orbit to Earth's. While both are rocky planets, Venus has an atmosphere much thicker and denser than Earth and any other rocky body in the Solar System. Its atmosphere is composed of mostly carbon dioxide (), with a global sulfuric acid cloud cover and no liquid water. At the mean surface level the atmosphere reaches a temperature of and a pressure 92 times greater than Earth's at sea level, turning the lowest layer of the atmosphere into a supercritical fluid. Venus is the third brightest object in Earth's sky, after the Moon and the Sun, and, like Mercury, appears always relatively close to the Sun, either as a "morning star" or an "evening star", resulting from orbiting closer ( inferior) to the Sun than Earth. The orbits of Venus and Earth make the two planets approach each other in synodic periods of 1.6 years ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NRLMSISE-00
NRLMSISE-00 is an empirical, global reference atmospheric model of the Earth from ground to space. It models the temperatures and densities of the atmosphere's components. A primary use of this model is to aid predictions of satellite orbital decay due to atmospheric drag. This model has also been used by astronomers to calculate the mass of air between telescopes and laser beams in order to assess the impact of laser guide stars on the non-lasing telescopes. Development The model, developed by Mike Picone, Alan Hedin, and Doug Drob, is based on the earlier models MSIS-86 and MSISE-90, but updated with actual satellite drag data. It also predicts anomalous oxygen. ''NRL'' stands for the US Naval Research Laboratory. MSIS stands for mass spectrometer and incoherent scatter radar, the two primary data sources for development of earlier versions of the model. ''E'' indicates that the model extends from the ground through exosphere and ''00'' is the year of release. Over the yea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atmosphere Of Earth
The atmosphere of Earth is composed of a layer of gas mixture that surrounds the Earth's planetary surface (both lands and oceans), known collectively as air, with variable quantities of suspended aerosols and particulates (which create weather features such as clouds and hazes), all retained by gravity of Earth, Earth's gravity. The atmosphere serves as a protective buffer between the Earth's surface and outer space, shields the surface from most meteoroids and ultraviolet solar irradiance, solar radiation, keeps it warm and reduces diurnal temperature variation (temperature extremes between daytime, day and night) through heat retention (greenhouse effect), redistributes heat and moisture among different regions via air currents, and provides the atmospheric chemistry, chemical and climate conditions allowing life to exist and evolution, evolve on Earth. By mole fraction (i.e., by quantity of molecules), dry air contains 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exponential Decay
A quantity is subject to exponential decay if it decreases at a rate proportional to its current value. Symbolically, this process can be expressed by the following differential equation, where is the quantity and (lambda Lambda (; uppercase , lowercase ; , ''lám(b)da'') is the eleventh letter of the Greek alphabet, representing the voiced alveolar lateral approximant . In the system of Greek numerals, lambda has a value of 30. Lambda is derived from the Phoen ...) is a positive rate called the exponential decay constant, disintegration constant, rate constant, or transformation constant: :\frac = -\lambda N(t). The solution to this equation (see #Solution_of_the_differential_equation, derivation below) is: :N(t) = N_0 e^, where is the quantity at time , is the initial quantity, that is, the quantity at time . Measuring rates of decay Mean lifetime If the decaying quantity, ''N''(''t''), is the number of discrete elements in a certain set (mathematics), se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sea Level
Mean sea level (MSL, often shortened to sea level) is an mean, average surface level of one or more among Earth's coastal Body of water, bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardised geodetic datumthat is used, for example, as a chart datum in cartography and Navigation, marine navigation, or, in aviation, as the standard sea level at which atmospheric pressure is measured to Calibration, calibrate altitude and, consequently, aircraft flight levels. A common and relatively straightforward mean sea-level standard is instead a long-term average of tide gauge readings at a particular reference location. The term ''above sea level'' generally refers to the height above mean sea level (AMSL). The term APSL means above present sea level, comparing sea levels in the past with the level today. Earth's radius at sea level is 6,378.137 km (3,963.191 mi) at the equator. It is 6,356.752 km (3,94 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ideal Gas
An ideal gas is a theoretical gas composed of many randomly moving point particles that are not subject to interparticle interactions. The ideal gas concept is useful because it obeys the ideal gas law, a simplified equation of state, and is amenable to analysis under statistical mechanics. The requirement of zero interaction can often be relaxed if, for example, the interaction is perfectly elastic or regarded as point-like collisions. Under various conditions of temperature and pressure, many real gases behave qualitatively like an ideal gas where the gas molecules (or atoms for monatomic gas) play the role of the ideal particles. Many gases such as nitrogen, oxygen, hydrogen, noble gases, some heavier gases like carbon dioxide and mixtures such as air, can be treated as ideal gases within reasonable tolerances over a considerable parameter range around standard temperature and pressure. Generally, a gas behaves more like an ideal gas at higher temperature and lower ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
