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Encyclopedia > Earth's atmosphere
A color image of Earth as seen from Apollo 17
Nitrogen 78.0842%
Oxygen 20.9463%
Argon 0.93422%
Carbon dioxide 0.03811%
Water vapor about 1%
Other 0.002%
Layers of the atmosphere (not to scale)

Earth's atmosphere is a layer of gases surrounding the planet Earth and retained by the Earth's gravity. It contains roughly (by molar content/volume) 78% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% carbon dioxide, trace amounts of other gases, and a variable amount (average around 1%) of water vapor. This mixture of gases is commonly known as air. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation and reducing temperature extremes between day and night. Look up air on Wiktionary, the free dictionary. ... Image File history File links Metadata Size of this preview: 599 × 599 pixelsFull resolution (3000 × 3002 pixel, file size: 6. ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... General Name, symbol, number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, period, block 16, 2, p Appearance colourless (gas) colourless (liquid) Standard atomic weight 15. ... General Name, symbol, number argon, Ar, 18 Chemical series noble gases Group, period, block 18, 3, p Appearance colorless Standard atomic weight 39. ... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Water vapor or water vapour (see spelling differences), also aqueous vapor, is the gas phase of water. ... The Other or constitutive other (also referred to as othering) is a key concept in continental philosophy, opposed to the Same. ... Image File history File links Atmosphere_layers. ... Image File history File links Atmosphere_layers. ... -1... This article is about Earth as a planet. ... Gravity is a force of attraction that acts between bodies that have mass. ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... General Name, symbol, number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, period, block 16, 2, p Appearance colourless (gas) colourless (liquid) Standard atomic weight 15. ... General Name, symbol, number argon, Ar, 18 Chemical series noble gases Group, period, block 18, 3, p Appearance colorless Standard atomic weight 39. ... Carbon dioxide in the Earths atmosphere is present in a low concentration. ... Water vapor or water vapour (see spelling differences), also aqueous vapor, is the gas phase of water. ... For other uses, see Atmosphere (disambiguation). ... Life on Earth redirects here. ... For other uses, see Ultraviolet (disambiguation). ... Solar irradiance spectrum at top of atmosphere. ... For other uses, see Temperature (disambiguation). ...


There is no definite boundary between the atmosphere and outer space. It slowly becomes thinner and fades into space. Three quarters of the atmosphere's mass is within 11 km of the planetary surface. In the United States, people who travel above an altitude of 80.5 km (50 statute miles) are designated astronauts. An altitude of 120 km (~75 miles or 400,000 ft) marks the boundary where atmospheric effects become noticeable during re-entry. The Kármán line, at 100 km (62 miles or 328,000 ft), is also frequently regarded as the boundary between atmosphere and outer space. Layers of Atmosphere - not to scale (NOAA)[1] Outer space, sometimes simply called space, refers to the relatively empty regions of the universe outside the atmospheres of celestial bodies. ... “km” redirects here. ... This article is about the astronomical term. ... Altitude is the elevation of an object from a known level or datum. ... A mile is any of several units of distance, or, in physics terminology, of length. ... For other uses, see Astronaut (disambiguation). ... Layers of Atmosphere - not to scale (NOAA)[1] Atmospheric gases scatter blue wavelengths of visible light more than other wavelengths, giving the Earth’s visible edge a blue halo. ...

Contents

Temperature and layers

The temperature of the Earth's atmosphere varies with altitude; the mathematical relationship between temperature and altitude varies among six different atmospheric layers (ordered highest to lowest): For other uses, see Temperature (disambiguation). ... Altitude is the elevation of an object from a known level or datum. ... The lapse rate is defined as the negative of the rate of change in an atmospheric variable, usually temperature, with height observed while moving upwards through an atmosphere. ...

  • Exosphere: from 500 – 1000 km (300 – 600 mi) up to 10,000 km (6,000 mi), free-moving particles that may migrate into and out of the magnetosphere or the solar wind.
exobase boundary
  • Ionosphere: is the part of the atmosphere that is ionized by solar radiation. It plays an important part 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. It is located in the thermosphere and is responsible for auroras.
thermopause boundary
  • Thermosphere: from 80 – 85 km (265,000 – 285,000 ft) to 640+ km (400+ mi), temperature increasing with height.
mesopause boundary
  • Mesosphere: From the Greek word "μέσος" meaning middle. The mesosphere extends from about 50 km (160,000 ft) to the range of 80 to 85 km (265,000 – 285,000 ft), temperature decreasing with height. This is also where most meteors burn up when entering the atmosphere.
stratopause boundary
  • Stratosphere: From the Latin word "stratus" meaning a spreading out. The stratosphere extends from the troposphere's 7 to 17 km (23,000 – 60,000 ft) range to about 50 km (160,000 ft). Temperature increases with height. The stratosphere contains the ozone layer, the part of the Earth's atmosphere which contains relatively high concentrations of ozone. "Relatively high" means a few parts per million—much higher than the concentrations in the lower atmosphere but still small compared to the main components of the atmosphere. It is mainly located in the lower portion of the stratosphere from approximately 15 to 35 km (50,000 – 115,000 ft) above Earth's surface, though the thickness varies seasonally and geographically.
tropopause boundary
  • Troposphere: From the Greek word "τρέπω" meaning to turn or change. The troposphere is the lowest layer of the atmosphere; it begins at the surface and extends to between 7 km (23,000 ft) at the poles and 17 km (60,000 ft) at the equator, with some variation due to weather factors. The troposphere has a great deal of vertical mixing due to solar heating at the surface. This heating warms air masses, which makes them less dense so they rise. When an air mass rises the pressure upon it decreases so it expands, doing work against the opposing pressure of the surrounding air. To do work is to expend energy, so the temperature of the air mass decreases. As the temperature decreases, water vapor in the air mass may condense or solidify, releasing latent heat that further uplifts the air mass. This process determines the maximum rate of decline of temperature with height, called the adiabatic lapse rate. It contains roughly 80% of the total mass of the atmosphere. 50% of the total mass of the atmosphere is located in the lower 5km of the troposphere.

The average temperature of the atmosphere at the surface of Earth is 15 °C (59 °F).[1] [fAgot png|thumb|200px|right|Atmosphere diagram showing the exosphere and other layers. ... A magnetosphere is the region around an astronomical object in which phenomena are dominated or organized by its magnetic field. ... The plasma in the solar wind meeting the heliopause The solar wind is a stream of charged particles (i. ... The exosphere (from the Greek words exo = out(side) and sphaira = ball) is the uppermost layer of the atmosphere. ... Relationship of the atmosphere and ionosphere The ionosphere is the uppermost part of the atmosphere, distinguished because it is ionized by solar radiation. ... The Aurora Borealis, or Northern Lights, shines above Bear Lake Aurora Borealis as seen over Canada at 11,000m (36,000 feet) Red and green Aurora in Fairbanks, Alaska Aurora Borealis redirects here. ... The Thermopause is the atmospheric boundary of Earths energy system, located at the top of the thermosphere. ... The thermosphere is the layer of the earths atmosphere directly above the mesosphere and directly below the exosphere. ... The mesosphere (from the Greek words mesos = middle and sfaira = ball) is the layer of the Earths atmosphere that is directly above the stratosphere and directly below the thermosphere. ... The mesosphere (from the Greek words mesos = middle and sphaira = ball) is the layer of the Earths atmosphere that is directly above the stratosphere and directly below the thermosphere. ... The stratopause is the level of the atmosphere which is the boundary between the stratosphere and the mesosphere. ... Atmosphere diagram showing stratosphere. ... For other uses, see Latin (disambiguation). ... For other uses, see Ozone (disambiguation). ... The tropopause is between the troposphere and the stratosphere. ... Atmosphere diagram showing the mesosphere and other layers. ... In thermochemistry, latent heat is the amount of energy in the form of heat released or absorbed by a substance during a change of phase (i. ... The adiabatic lapse rate is the rate of temperature change that occurs in an atmosphere as a function of elevation, assuming that air behaves adiabatically. ... For other uses, see Celsius (disambiguation). ... For other uses, see Fahrenheit (disambiguation). ...


Pressure and thickness

Main article: Atmospheric pressure
Barometric Formula: (used for airplane flight) barometric formula
One mathematical model: NRLMSISE-00

The average atmospheric pressure, at sea level, is about 101.3 kilopascals (about 14.7 psi); total atmospheric mass is 5.1361×1018 kg [1]. Diurnal (daily) rhythm of air pressure in northern Germany (black curve is air pressure) Atmospheric pressure is the pressure at any point in the Earths atmosphere. ... Aviation encompasses all the activities relating to airborne devices created by human ingenuity, generally known as aircraft. ... The barometric formula, sometimes called the exponential atmosphere or isothermal atmosphere, is a formula used to model how the pressure (or density) of the air changes with altitude. ... NRLMSISE output The NRLMSISE-00 is an empirical, global model of the Earths atmosphere from ground to space. ... For considerations of sea level change, in particular rise associated with possible global warming, see sea level rise. ... The pascal (symbol Pa) is the SI unit of pressure. ... A pressure gauge reading in PSI (red scale) and kPa (black scale) The pound-force per square inch (symbol: lbf/in2) is a non-SI unit of pressure based on avoirdupois units. ...


Atmospheric pressure is a direct result of the total weight of the air above the point at which the pressure is measured. This means that air pressure varies with location and time, because the amount (and weight) of air above the earth varies with location and time.


Atmospheric pressure decreases with height, dropping by 50% at an altitude of about 5.6 km (18,000 ft). Equivalently, about 50% of the total atmospheric mass is within the lowest 5.6 km. This pressure drop is approximately exponential, so that pressure decreases by approximately half every 5.6 km. However, because of changes in temperature throughout the atmospheric column, as well as the fact that the force of gravity begins to decrease at great altitudes, a single equation does not model atmospheric pressure through all altitudes (it is modeled in 7 exponentially decreasing layers, in the equations given above).


Even in the exosphere, the atmosphere is still present (as can be seen for example by the effects of atmospheric drag on satellites). For other uses, see Satellite (disambiguation). ...


The equations of pressure by altitude in the above references can be used directly to estimate atmospheric thickness. However, the following published data are given for reference:- [2]

  • 50% of the atmosphere by mass is below an altitude of 5.6 km.
  • 90% of the atmosphere by mass is below an altitude of 16 km. The common cruising altitude of commercial airliners is about 10 km.
  • 99.99997% of the atmosphere by mass is below 100 km. The highest X-15 plane flight in 1963 reached an altitude of 354,300 ft or 108 km.

Therefore, most of the atmosphere (99.9997%) is below 100 km, although in the rarefied region above this there are auroras and other atmospheric effects. The North American X-15 rocket plane was part of the USAF/NASA/USN X-series of experimental aircraft, including also the Bell X-1. ... The Aurora Borealis, or Northern Lights, shines above Bear Lake Aurora Borealis as seen over Canada at 11,000m (36,000 feet) Red and green Aurora in Fairbanks, Alaska Aurora Borealis redirects here. ...


Composition

Composition of Earth's atmosphere as at 1987.Dec. The lower pie represents the least common gases that compose 0.038% of the atmosphere. Values normalized for illustration.
Composition of Earth's atmosphere as at 1987.Dec. The lower pie represents the least common gases that compose 0.038% of the atmosphere. Values normalized for illustration.
Mean atmospheric water vapor
Mean atmospheric water vapor
Composition of
dry atmosphere, by volume
[3]
ppmv: parts per million by volume
Gas Volume
Nitrogen (N2) 780,840 ppmv (78.084%)
Oxygen (O2) 209,460 ppmv (20.946%)
Argon (Ar) 9,340 ppmv (0.9340%)
Carbon dioxide (CO2) 383 ppmv (0.0383%)
Neon (Ne) 18.18 ppmv (0.001818%)
Helium (He) 5.24 ppmv (0.000524%)
Methane (CH4) 1.745 ppmv (0.0001745%)
Krypton (Kr) 1.14 ppmv (0.000114%)
Hydrogen (H2) 0.55 ppmv (0.000055%)
Not included in above dry atmosphere:
Water vapor (H2O) ~0.25% over full atmosphere, typically 1% to 4% near surface
Minor components of air not listed above include[citation needed]
Gas Volume
nitrous oxide 0.3 ppmv (0.00005%)
xenon 0.09 ppmv (9x10-6%)
ozone 0.0 to 0.07 ppmv (0%-7x10-6%)
nitrogen dioxide 0.02 ppmv (2x10-6%)
iodine 0.01 ppmv (1x10-6%)
carbon monoxide trace
ammonia trace

The mean molar mass of air is 28.97 g/mol. Note that the composition figures above are by volume-fraction (V%), which for ideal gases is equal to mole-fraction (that is, fraction of total molecules). By contrast, mass-fraction abundances of gases, particularly for gases with significantly different molecular (molar) mass from that of air will differ from those by volume. For example, in air, helium is 5.2 ppm by volume-fraction and mole-fraction, but only about (4/29) × 5.2 ppm = 0.72 ppm by mass-fraction. Image File history File links Atmosphere_gas_proportions. ... Image File history File links Atmosphere_gas_proportions. ... Download high resolution version (2431x1280, 1267 KB)Global mean atmospheric water vapor. ... Download high resolution version (2431x1280, 1267 KB)Global mean atmospheric water vapor. ... Parts per million (ppm) is a measure of concentration that is used where low levels of concentration are significant. ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... General Name, symbol, number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, period, block 16, 2, p Appearance colourless (gas) colourless (liquid) Standard atomic weight 15. ... General Name, symbol, number argon, Ar, 18 Chemical series noble gases Group, period, block 18, 3, p Appearance colorless Standard atomic weight 39. ... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... For other uses, see Neon (disambiguation). ... General Name, symbol, number helium, He, 2 Chemical series noble gases Group, period, block 18, 1, s Appearance colorless Standard atomic weight 4. ... Methane is a chemical compound with the molecular formula . ... For other uses, see Krypton (disambiguation). ... This article is about the chemistry of hydrogen. ... Water vapor or water vapour (see spelling differences), also aqueous vapor, is the gas phase of water. ... For other uses, see Nitrous oxide (disambiguation). ... General Name, Symbol, Number xenon, Xe, 54 Chemical series noble gases Group, Period, Block 18, 5, p Appearance colorless Standard atomic weight 131. ... For other uses, see Ozone (disambiguation). ... [1] R-phrases , S-phrases , , , , , Supplementary data page Structure and properties n, εr, etc. ... For other uses, see Iodine (disambiguation). ... R-phrases , , , , S-phrases , , , , Flash point Flammable gas Related Compounds Related oxides carbon dioxide; carbon suboxide; dicarbon monoxide; carbon trioxide Supplementary data page Structure and properties n, εr, etc. ... For other uses, see Ammonia (disambiguation). ... An ideal gas or perfect gas is a hypothetical gas consisting of identical particles of zero volume, with no intermolecular forces. ...


Heterosphere

Below the turbopause at an altitude of about 100 km (not far from the mesopause), the Earth's atmosphere has a more-or-less uniform composition (apart from water vapor) as described above; this constitutes the homosphere.[4] However, above about 100 km, the Earth's atmosphere begins to have a composition which varies with altitude. This is essentially because, in the absence of mixing, the density of a gas falls off exponentially with increasing altitude, but at a rate which depends on the molar mass. Thus higher mass constituents, such as oxygen and nitrogen, fall off more quickly than lighter constituents such as helium, molecular hydrogen, and atomic hydrogen. Thus there is a layer, called the heterosphere, in which the earth's atmosphere has varying composition. As the altitude increases, the atmosphere is dominated successively by helium, molecular hydrogen, and atomic hydrogen. The precise altitude of the heterosphere and the layers it contains varies significantly with temperature. After loss of the hydrogen, helium and other hydrogen-containing gases from early Earth due to the Sun's radiation, primitive Earth was devoid of an atmosphere. The first atmosphere was formed by outgassing of gases trapped in the interior of the early Earth, which still goes on today in volcanoes. [5] The turbopause marks the altitude in the Earths atmosphere below which turbulent mixing dominates. ... Molar mass is the mass of one mole of a chemical element or chemical compound. ... General Name, symbol, number helium, He, 2 Chemical series noble gases Group, period, block 18, 1, s Appearance colorless Standard atomic weight 4. ... This article is about the chemistry of hydrogen. ...


Density and mass

Main article: Density of air
Earth's atmosphere from space

The density of air at sea level is about 1.2 kg/m³(1.2 g/L). Natural variations of the barometric pressure occur at any one altitude as a consequence of weather. This variation is relatively small for inhabited altitudes but much more pronounced in the outer atmosphere and space due to variable solar radiation. The density of air, ρ (Greek: rho) (air density), is the mass per unit volume of Earths atmosphere, and is a useful value in aeronautics. ... Image File history File links Download high-resolution version (676x640, 266 KB) Andes Mountains as seen from Gemini 7. ... Image File history File links Download high-resolution version (676x640, 266 KB) Andes Mountains as seen from Gemini 7. ... Diurnal (daily) rhythm of air pressure in northern Germany (black curve is air pressure) Atmospheric pressure is the pressure at any point in the Earths atmosphere. ...

Temperature and mass density against altitude from the NRLMSISE-00 standard atmosphere model
Temperature and mass density against altitude from the NRLMSISE-00 standard atmosphere model

The atmospheric density decreases as the altitude increases. This variation can be approximately modeled using the barometric formula. More sophisticated models are used by meteorologists and space agencies to predict weather and orbital decay of satellites. Image File history File links Atmosphere_model. ... Image File history File links Atmosphere_model. ... NRLMSISE output The NRLMSISE-00 is an empirical, global model of the Earths atmosphere from ground to space. ... Atmospheric pressure is the pressure caused by the weight of air above any area in the Earths atmosphere. ... The barometric formula, sometimes called the exponential atmosphere or isothermal atmosphere, is a formula used to model how the pressure (or density) of the air changes with altitude. ...


The average mass of the atmosphere is about 5,000 trillion metric tons or 1/1,200,000 the mass of Earth. According to the National Center for Atmospheric Research, "The total mean mass of the atmosphere is 5.1480×1018 kg with an annual range due to water vapor of 1.2 or 1.5×1015 kg depending on whether surface pressure or water vapor data are used; somewhat smaller than the previous estimate. The mean mass of water vapor is estimated as 1.27×1016 kg and the dry air mass as 5.1352 ±0.0003×1018 kg."


Evolution on Earth

See also: History of Earth
Atmospheric gases scatter blue light more than other wavelengths, giving the Earth a blue halo when seen from space.
Atmospheric gases scatter blue light more than other wavelengths, giving the Earth a blue halo when seen from space.

The history of the Earth's atmosphere prior to one billion years ago is poorly understood and an active area of scientific research. The following discussion presents a plausible scenario. Geological time put in a diagram called a geological clock, showing the relative lengths of the eons of the Earths history. ... Image File history File links Size of this preview: 800 × 531 pixelsFull resolution (3027 × 2010 pixel, file size: 543 KB, MIME type: image/jpeg) Identification Mission: ISS013 Roll: E Frame: 54329 Mission ID on the Film or image: ISS013 Country or Geographic Name: Features: EARTH LIMB, MOON, CLOUD TOPS Center... Image File history File links Size of this preview: 800 × 531 pixelsFull resolution (3027 × 2010 pixel, file size: 543 KB, MIME type: image/jpeg) Identification Mission: ISS013 Roll: E Frame: 54329 Mission ID on the Film or image: ISS013 Country or Geographic Name: Features: EARTH LIMB, MOON, CLOUD TOPS Center... Rayleigh scattering causing the blue hue of the sky and the reddening at sunset Rayleigh scattering (named after Lord Rayleigh) is the scattering of light, or other electromagnetic radiation, by particles much smaller than the wavelength of the light. ... It has been suggested that Moon dog be merged into this article or section. ...


The modern atmosphere is sometimes referred to as Earth's "third atmosphere", in order to distinguish the current chemical composition from two notably different previous compositions. The original atmosphere was primarily helium and hydrogen. Heat from the still-molten crust, and the sun, plus a probably enhanced solar wind, dissipated this atmosphere. A chemical substance is any material substance used in or obtained by a process in chemistry: A chemical compound is a substance consisting of two or more chemical elements that are chemically combined in fixed proportions. ... General Name, symbol, number helium, He, 2 Chemical series noble gases Group, period, block 18, 1, s Appearance colorless Standard atomic weight 4. ... This article is about the chemistry of hydrogen. ... For other uses, see Heat (disambiguation) In physics, heat, symbolized by Q, is energy transferred from one body or system to another due to a difference in temperature. ... Earth cutaway from core to exosphere. ... The plasma in the solar wind meeting the heliopause The solar wind is a stream of charged particles (i. ...


About 4.4 billion years ago, the surface had cooled enough to form a crust, still heavily populated with volcanoes which released steam, carbon dioxide, and ammonia. This led to the early "second atmosphere", which was primarily carbon dioxide and water vapor, with some nitrogen but virtually no oxygen. This second atmosphere had approximately 100 times as much gas as the current atmosphere, but as it cooled much of the carbon dioxide was dissolved in the seas and precipitated out as carbonates. The later "second atmosphere" contained largely nitrogen and carbon dioxide. However, simulations run at the University of Waterloo and University of Colorado in 2005 suggest that it may have had up to 40% hydrogen.[6] It is generally believed that the greenhouse effect, caused by high levels of carbon dioxide and methane, kept the Earth from freezing. Cleveland Volcano in the Aleutian Islands of Alaska photographed from the International Space Station For other uses, see Volcano (disambiguation). ... For other uses, see Steam (disambiguation). ... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... For other uses, see Ammonia (disambiguation). ... Water vapor or water vapour (see spelling differences), also aqueous vapor, is the gas phase of water. ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... General Name, symbol, number oxygen, O, 8 Chemical series nonmetals, chalcogens Group, period, block 16, 2, p Appearance colourless (gas) colourless (liquid) Standard atomic weight 15. ... Gas phase particles (atoms, molecules, or ions) move around freely Gas is one of the four major states of matter, consisting of freely moving atoms or molecules without a definite shape and without a definite volume. ... Ball-and-stick model of the carbonate ion, CO32− For other meanings, see Carbonate (disambiguation) In chemistry, a carbonate is a salt or ester of carbonic acid. ... Wikinews has related news: Scientists warn thawing Siberia may trigger global meltdown A schematic representation of the exchanges of energy between outer space, the Earths atmosphere, and the Earth surface. ... Methane is a chemical compound with the molecular formula . ... In physics and chemistry, freezing is the process whereby a liquid turns to a solid. ...


One of the earliest types of bacteria was the cyanobacteria. Fossil evidence indicates that bacteria shaped like these existed approximately 3.3 billion years ago and were the first oxygen-producing evolving phototropic organisms. They were responsible for the initial conversion of the earth's atmosphere from an anoxic state to an oxic state (that is, from a state without oxygen to a state with oxygen) during the period 2.7 to 2.2 billion years ago. Being the first to carry out oxygenic photosynthesis, they were able to produce oxygen while sequestering carbon dioxide in organic molecules, playing a major role in oxygenating the atmosphere. Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Orders The taxonomy is currently under revision. ... For other uses, see Fossil (disambiguation). ... The Oxygen Catastrophe was a massive environmental change believed to have happened during the Siderian period at the beginning of the Paleoproterozoic era. ...


Photosynthesising plants would later evolve and continue releasing oxygen and sequestering carbon dioxide. Over time, excess carbon became locked in fossil fuels, sedimentary rocks (notably limestone), and animal shells. As oxygen was released, it reacted with ammonia to release nitrogen; in addition, bacteria would also convert ammonia into nitrogen. But most of the nitrogen currently present in the atmosphere results from sunlight-powered photolysis of ammonia released steadily over the aeons from volcanoes. The leaf is the primary site of photosynthesis in plants. ... This article is about evolution in biology. ... Fossil fuels are hydrocarbon-containing natural resources such as coal, petroleum and natural gas. ... Two types of sedimentary rock: limey shale overlaid by limestone. ... For other uses, see Limestone (disambiguation). ... Various seashells Danielle A shell is the hard, rigid outer covering, or integument, allanimals. ... Photolysis refers to any chemical reaction in which a compound is broken down by light. ...


As more plants appeared, the levels of oxygen increased significantly, while carbon dioxide levels dropped. At first the oxygen combined with various elements (such as iron), but eventually oxygen accumulated in the atmosphere, resulting in mass extinctions and further evolution. With the appearance of an ozone layer (ozone is an allotrope of oxygen) lifeforms were better protected from ultraviolet radiation. This oxygen-nitrogen atmosphere is the "third atmosphere". 200 – 250 million years ago, up to 35 percent of the atmosphere was oxygen (bubbles of ancient atmosphere were found in an amber). The periodic table of the chemical elements A chemical element, or element, is a type of atom that is defined by its atomic number; that is, by the number of protons in its nucleus. ... For other uses, see Iron (disambiguation). ... An extinction event (also extinction-level event, ELE) is a period in time when a large number of species die out. ... The ozone layer is a layer in Earths atmosphere which contains relatively high concentrations of ozone (O3). ... Allotropy (Gr. ... Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. ...


This modern atmosphere has a composition which is enforced by oceanic blue-green algae as well as geological processes. O2 does not remain naturally free in an atmosphere, but tends to be consumed (by inorganic chemical reactions, as well as by animals, bacteria, and even land plants at night), while CO2 tends to be produced by respiration and decomposition and oxidation of organic matter. Oxygen would vanish within a few million years due to chemical reactions and CO2 dissolves easily in water and would be gone in millennia if not replaced. Both are maintained by biological productivity and geological forces seemingly working hand-in-hand to maintain reasonably steady levels over millions of years (see Gaia theory). Cyanobacteria (Greek: cyanos = blue) are a phylum of aquatic bacteria that obtain their energy through photosynthesis. ... In animal physiology, respiration is the transport of oxygen from the ambient air to the tissue cells and the transport of carbon dioxide in the opposite direction. ... For other uses, see Decomposition (disambiguation). ... The most fundamental reactions in chemistry are the redox processes. ... A Gaia theory is a class of scientific models of the biosphere in which life fosters and maintains suitable conditions for itself by affecting Earths environment. ...


Air pollution

Before desulfurization filters were installed, the emissions from this power plant in New Mexico contained excessive amounts of sulfur dioxide.
Before desulfurization filters were installed, the emissions from this power plant in New Mexico contained excessive amounts of sulfur dioxide.
Main article: Air pollution

Air pollution is a chemical, physical (e.g. particulate matter) or biological agent that modifies the natural characteristics of the atmosphere in an unwanted way. Stratospheric ozone depletion due to air pollution (chiefly from chlorofluorocarbons) has long been recognized as a threat to human health as well as to the earth's ecosystems. Wikipedia does not have an article with this exact name. ... Wikipedia does not have an article with this exact name. ... Flue gas desulfurization is technology that employs a sorbent, usually lime or limestone, to remove sulfur dioxide(SO2) from the gases produced by burning fossil fuels. ... Capital Santa Fe Largest city Albuquerque Largest metro area Albuquerque metropolitan area Area  Ranked 5th  - Total 121,665 sq mi (315,194 km²)  - Width 342 miles (550 km)  - Length 370 miles (595 km)  - % water 0. ... Sulfur dioxide (or Sulphur dioxide) has the chemical formula SO2. ... Air pollution is the modification of the natural characteristics of the atmosphere by a chemical, particulate matter, or biological agent. ... A chemical substance is any material substance used in or obtained by a process in chemistry: A chemical compound is a substance consisting of two or more chemical elements that are chemically combined in fixed proportions. ... A magnet levitating above a high-temperature superconductor demonstrates the Meissner effect. ... Particulates, alternatively referred to as particulate matter (PM), aerosols or fine particles, are tiny particles of solid or liquid suspended in a gas. ... Biological material may refer to: Biological tissue, or just tissue Biomass, living or dead biological matter, often plants grown as fuel Biomass (ecology), the total mass of living biological matter Biomolecule, a chemical compound that naturally occurs in living organisms Biotic material, from living things Bio-based material, a processed... Atmosphere diagram showing stratosphere. ... Global monthly average total ozone amount Ozone depletion describes two distinct, but related observations: a slow, steady decline of about 4 percent per decade in the total amount of ozone in Earths stratosphere since around 1980; and a much larger, but seasonal, decrease in stratospheric ozone over Earths... For other uses, see CFC (disambiguation). ... A coral reef near the Hawaiian islands is an example of a complex marine ecosystem. ...


Worldwide air pollution is responsible for large numbers of deaths and cases of respiratory disease. Enforced air quality standards, like the Clean Air Act in the United States, have reduced the presence of some pollutants. While major stationary sources are often identified with air pollution, the greatest source of emissions is actually mobile sources, principally the automobile. Gases such as carbon dioxide, methane, and fluorocarbons contribute to global warming, and these gases, or excess amounts of some emitted from fossil fuel burning, have recently been identified by the United States and many other countries (see Kyoto accord), as pollutants. Diseases of the mammalian respiratory system are classified under one of two broad categories: physiologic, where disease states are characterised by alterations in physiology, or anatomical, where disease states are defined by the anatomical location/level affected, or by the layers of the respiratory system affected by disease. ... This article or section does not adequately cite its references or sources. ... A major stationary source is a pollutant as defined by the Environmental Protection Agency. ... The AP 42 Compilation of Air Pollutant Emission Factors, was first published by the U.S. Public Health Service in 1968. ... “Car” and “Cars” redirect here. ... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Methane is a chemical compound with the molecular formula . ... Some important fluorocarbons. ... Global warming refers to the increase in the average temperature of the Earths near-surface air and oceans in recent decades and its projected continuation. ... Earth as seen by Apollo 17 The Kyoto Protocol is an amendment to the United Nations Framework Convention on Climate Change (UNFCCC), an international treaty on global warming. ...


References

  1. ^ Earth's Radiation Balance and Oceanic Heat Fluxes.
  2. ^ Lutgens, Frederick K. and Edward J. Tarbuck (1995) The Atmosphere, Prentice Hall, 6th ed., pp14-17, ISBN 0-13-350612-6
  3. ^ Source for figures: Carbon dioxide, NASA Earth Fact Sheet, (updated 2007.01). Methane, IPCC TAR table 6.1, (updated to 1998). The NASA total was 17 ppmv over 100%, and CO2 was increased here by 15 ppmv. To normalize, N2 should be reduced by about 25 ppmv and O2 by about 7 ppmv.
  4. ^ homosphere—AMS Glossary
  5. ^ Vercheval, J. The thermosphere: a part of the heterosphere. (offline, see Internet Archive copy)
  6. ^ "Early Earth atmosphere favorable to life: study", University of Waterloo, April 7, 2005. Retrieved on 2007-07-30. 

IPCC is science authority for the UNFCCC The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 by two United Nations organizations, the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) to assess the risk of human-induced climate change. The Panel is open to all... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 211th day of the year (212th in leap years) in the Gregorian calendar. ...

See also

Atmosphere Portal

Image File history File links Portal. ... This article needs cleanup. ... Air glow is a term for light emmited from the upper layers of the atmosphere of Earth, or of another planet. ... An airshed is a part of the atmosphere that behaves in a coherent way with respect to the dispersion of emissions. ... For other uses, see Atmosphere (disambiguation). ... Atmospheric chemistry is a branch of atmospheric science in which the chemistry of the Earths atmosphere and that of other planets is studied. ... Atmospheric dispersion modeling is performed with computer programs that use mathematical equations and algorithms to simulate how pollutants in the ambient atmosphere disperse in the atmosphere. ... Cloud to ground Lightning in the global atmospheric electrical circuit. ... Atmospheric models are mathematical representations of the atmosphere, generally for the Earth. ... Aviation encompasses all the activities relating to airborne devices created by human ingenuity, generally known as aircraft. ... For other uses, see Biosphere (disambiguation). ... Compressed air is used to refer to: Pneumatics, the use of pressurized gases to do work, as used in the Air car Breathing gas, often used in scuba diving, also to inflate buoyancy devices Compressed air can also be used for cooling using a vortex tube. ... Global warming refers to the increase in the average temperature of the Earths near-surface air and oceans in recent decades and its projected continuation. ... Wikinews has related news: Scientists warn thawing Siberia may trigger global meltdown A schematic representation of the exchanges of energy between outer space, the Earths atmosphere, and the Earth surface. ... The historical temperature record shows the fluctuations of the temperature of the atmosphere and the oceans throughout history, and in particular since 1850. ... The movement of water around, over, and through the Earth is called the water cycle, a key process of the hydrosphere. ... IPCC is the science authority for the UNFCCC The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 by two United Nations organizations, the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP), to evaluate the risk of climate change brought on by humans, based mainly on... The tectonic plates of the Lithosphere on Earth. ... // Meteorology (from Greek: μετέωρον, meteoron, high in the sky; and λόγος, logos, knowledge) is the interdisciplinary scientific study of the atmosphere that focuses on weather processes and forecasting. ... The U.S. Standard Atmosphere is a series of models that define values for atmospheric temperature, density, pressure and other properties over a wide range of altitudes. ...

External links

Another depiction of the layers of the atmosphere.
Another depiction of the layers of the atmosphere.
Wikimedia Commons has media related to:

Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Image File history File links Commons-logo. ... Atmosphere diagram showing the mesosphere and other layers. ... Atmosphere diagram showing stratosphere. ... The mesosphere (from the Greek words mesos = middle and sphaira = ball) is the layer of the Earths atmosphere that is directly above the stratosphere and directly below the thermosphere. ... The thermosphere is the layer of the earths atmosphere directly above the mesosphere and directly below the exosphere. ... [fAgot png|thumb|200px|right|Atmosphere diagram showing the exosphere and other layers. ... The tropopause is between the troposphere and the stratosphere. ... The stratopause is the level of the atmosphere which is the boundary between the stratosphere and the mesosphere. ... The mesosphere (from the Greek words mesos = middle and sfaira = ball) is the layer of the Earths atmosphere that is directly above the stratosphere and directly below the thermosphere. ... The Thermopause is the atmospheric boundary of Earths energy system, located at the top of the thermosphere. ... The exosphere (from the Greek words exo = out(side) and sphaira = ball) is the uppermost layer of the atmosphere. ... The ozone layer is a layer in Earths atmosphere which contains relatively high concentrations of ozone (O3). ... The turbopause marks the altitude in the Earths atmosphere below which turbulent mixing dominates. ... Relationship of the atmosphere and ionosphere The ionosphere is the uppermost part of the atmosphere, distinguished because it is ionized by solar radiation. ... For other uses, see Atmosphere (disambiguation). ... Venus, the second planet from the Sun, has an atmosphere very different from that of Earth. ... Mars, the fourth planet from the Sun, has a very different atmosphere from that of Earth. ... This article is about the planet Saturns largest natural satellite. ... The bland face of Uranus, as imaged by Voyager 2 in 1986. ... Image File history File links Size of this preview: 800 × 531 pixelsFull resolution (3027 × 2010 pixel, file size: 543 KB, MIME type: image/jpeg) Identification Mission: ISS013 Roll: E Frame: 54329 Mission ID on the Film or image: ISS013 Country or Geographic Name: Features: EARTH LIMB, MOON, CLOUD TOPS Center... Mercurys primordial atmosphere dissipated shortly after the planets formation because of both the low level of gravity on the planet, the high temperature,and the effects of the solar wind. ... The atmosphere of the Moon is very tenuous and insignificant in comparison to that of the Earth. ... This article is about the physical universe. ... This article is about Earth as a planet. ... Geological time put in a diagram called a geological clock, showing the relative lengths of the eons of the Earths history. ... Earth science (also known as geoscience, the geosciences or the Earth Sciences), is an all-embracing term for the sciences related to the planet Earth. ... Earth cutaway from core to exosphere. ... The tectonic plates of the world were mapped in the second half of the 20th century. ... Geological time scale. ... This article includes a list of works cited but its sources remain unclear because it lacks in-text citations. ... For the geological process, see Weathering or Erosion. ... This article is about life in general. ... For other uses, see Biosphere (disambiguation). ... For the definition, see Life. ... A cluster of Escherichia coli bacteria magnified 10,000 times. ... For other uses, see Plant (disambiguation). ... For the fictional character, see Fungus the Bogeyman. ... Fauna is a collective term for animal life of any particular region or time. ... For other uses, see Animal (disambiguation). ... For the song by Girls Aloud see Biology (song) Biology studies the variety of life (clockwise from top-left) E. coli, tree fern, gazelle, Goliath beetle Biology (from Greek: βίος, bio, life; and λόγος, logos, speech lit. ... The evolutionary history of life and the origin of life are fields of ongoing geological and biological research. ... For other uses, see Wilderness (disambiguation). ... For the journal, see Ecology (journal). ... A coral reef near the Hawaiian islands is an example of a complex marine ecosystem. ... For other uses, see Universe (disambiguation). ... This article is about matter in physics and chemistry. ... Green people redirects here. ... Layers of Atmosphere - not to scale (NOAA)[1] Outer space, sometimes simply called space, refers to the relatively empty regions of the universe outside the atmospheres of celestial bodies. ...


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