Atmospheric gases scatter blue light more than other wavelengths, giving the Earth a blue halo when seen from space. Rayleigh scattering (named after Lord Rayleigh) is the elastic Scattering of Light or other electromagnetic radiation by particles much smaller A halo (ἅλως also known as a nimbus, icebow or Gloriole) is an Optical phenomenon that appears near or around the Sun or
Nitrogen	78. Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 0842%
Oxygen	20. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the 9463%
Argon	0. This article pertains to the chemical element For other uses see Argon (disambiguation. 93422%
Carbon dioxide	0. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single 03811%
Water vapor	about 1%
Other	0. General properties of water vapor Evaporation/sublimation Whenever a water molecule leaves a surface it is said to have evaporated The Other or constitutive other (also referred to as othering) is a key concept in Continental philosophy, opposed to the Same 002%

Layers of the atmosphere (not to scale)

The Earth's atmosphere is a layer of gases surrounding the planet Earth and retained by the Earth's gravity. This page is about the physical properties of gas as a state of matter EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 Gravitation is a natural Phenomenon by which objects with Mass attract one another It contains roughly (by molar content/volume) 78. 08% nitrogen, 20. Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 95% oxygen, 0. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the 93% argon, 0. This article pertains to the chemical element For other uses see Argon (disambiguation. 038% carbon dioxide, trace amounts of other gases, and a variable amount (average around 1%) of water vapor. Carbon dioxide forms approximately 004% of the Earth's atmosphere. General properties of water vapor Evaporation/sublimation Whenever a water molecule leaves a surface it is said to have evaporated 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. An atmosphere (from Greek ατμός - atmos, " Vapor " + σφαίρα - sphaira, " Sphere " Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature

There is no definite boundary between the atmosphere and outer space. Outer space, often simply called space, comprises the relatively empty regions of the Universe outside the escape velocities of Celestial bodies. It slowly becomes thinner and fades into space. Three quarters of the atmosphere's mass is within 11 km of the planetary surface. A planet, as defined by the International Astronomical Union (IAU is a celestial body Orbiting a Star or stellar remnant that is In the United States, people who travel above an altitude of 80. The United States of America —commonly referred to as the Altitude is the Elevation of a point or object from a known level or datum (plural data 5 km (50 statute miles) are designated astronauts. A mile is a unit of Length, usually used to measure Distance, in a number of different systems including Imperial units United States An astronaut or cosmonaut (космона́вт) is a person trained 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.

Temperature and layers

The temperature of the Earth's atmosphere varies with altitude; the mathematical relationship between temperature and altitude varies among five different atmospheric layers (ordered highest to lowest, the ionosphere is part of the thermosphere):

• 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. Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature Altitude is the Elevation of a point or object from a known level or datum (plural data The lapse rate is defined as the negative of the rate of change in an atmospheric variable usually Temperature, with height in an atmosphere The exosphere is the uppermost layer of the atmosphere. On Earth, its lower boundary at the edge of the Thermosphere is estimated to be 500 km to A magnetosphere' is a highly magnetized region around and possessed by an Astronomical object. The solar wind is a Stream of charged particles&mdasha plasma &mdashthat are ejected from the upper atmosphere of the Sun.

• Ionosphere: is the part of the atmosphere that is ionized by solar radiation. The exosphere is the uppermost layer of the atmosphere. On Earth, its lower boundary at the edge of the Thermosphere is estimated to be 500 km to The ionosphere is the uppermost part of the atmosphere, distinguished because it 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.

• Thermosphere: from 80 – 85 km (265,000 – 285,000 ft) to 640+ km (400+ mi), temperature increasing with height. The Thermopause is the atmospheric boundary of Earth's energy system located at the top of the Thermosphere. The thermosphere is the layer of the Earth's atmosphere directly above the Mesosphere and directly below the Exosphere.

• Mesosphere: From the Greek word "μέσος" meaning middle. The mesopause is the temperature minimum at the boundary between the Mesosphere and the Thermosphere atmospheric regions This article is about the atmospheric mesosphere for the Earth's mantle see Mesosphere (mantle. 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.

• Stratosphere: From the Latin word "stratus" meaning a spreading out. The stratopause is the level of the atmosphere which is the boundary between two layers Stratosphere and the Mesosphere. The stratosphere is the second major layer of Earth's atmosphere, just above the Troposphere, and below the Mesosphere. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. 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. OZONE is an object oriented Operating system written in the C programming language. "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.

• Troposphere: From the Greek word "τρέπω" meaning to turn or change. The tropopause is in the atmosphere between the Troposphere and the Stratosphere. The troposphere is the lowest portion of Earth's atmosphere. It contains approximately 75% of the atmosphere's mass and almost all of its Water vapor and Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly 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. In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός As the temperature decreases, water vapor in the air mass may condense or solidify, releasing latent heat that further uplifts the air mass. 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 This process determines the maximum rate of decline of temperature with height, called the adiabatic lapse rate. The lapse rate is defined as the negative of the rate of change in an atmospheric variable usually Temperature, with height in an atmosphere It contains roughly 80% of the total mass of the atmosphere. 50% of the total mass of the atmosphere is located in the lower 5 km of the troposphere.

The average temperature of the atmosphere at the surface of Earth is 15 °C (59 °F). The Celsius Temperature scale was previously known as the centigrade scale. Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724 ^[1][2]

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. Aviation refers to activities involving man-made flying devices ( Aircraft) including the people organizations and regulatory bodies involved with them The barometric formula, sometimes called the exponential atmosphere or Isothermal Atmosphere, is a Formula used NRLMSISE-00 is an Empirical, global model of the Earth's atmosphere from ground to space Mean sea level (MSL is the average (mean height of the Sea, with reference to a suitable reference surface 3 kilopascals (about 14. 7 psi); total atmospheric mass is 5. The pound per square inch or more accurately pound-force per square inch (symbol psi or lbf/in² or lbf/in²) is a unit of 1480×10¹⁸ kg ^[3].

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. However the average mass of the air above a square meter of the earth's surface is known to the same high accuracy as the total air mass of 5148. 0 teratonnes and area of the earth of 51007. 2 megahectares, namely 5148. 0/510. 072 = 10. 093 metric tonnes or 14. 356 lbs (mass) per square inch. This is about 2. 5% below the officially standardized unit atmosphere (1 atm) of 101. 325 kPa or 14. 696 psi, and corresponds to the mean pressure not at sea level but at the mean base of the atmosphere as contoured by the earth's terrain.

Atmospheric pressure decreases with height, dropping by 50% at an altitude of about 5. 6 km (18,000 ft). For comparison: the highest mountain, Mount Everest, is higher, at 8. Mount Everest, also called Sagarmatha (सगरमाथा meaning Head of the Sky) or Chomolungma, Qomolangma or Zhumulangma (in 8 km, which is why it is so difficult to climb without supplemental oxygen. 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). In Fluid dynamics, drag (sometimes called fluid resistance) is the force that resists the movement of a Solid object through a Fluid (a This article is about artificial satellites For natural satellites also known as moons see Natural satellite.

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:- ^[4]

• 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 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 (108,000 m).

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.

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.

Mean atmospheric water vapor

The mean molar mass of air is 28. Carbon monoxide, with the chemical formula CO is a colorless odorless tasteless yet highly toxic Gas. Ammonia is a compound with the formula N[[hydrogen H3]] It is normally encountered as a Gas with a characteristic pungent Odor 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). These four properties that constitute an ideal gas can be easily remembered by the acronym RIPE which stands for - R andom Motion (molecules are in constant random motion 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.

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. The turbopause marks the altitude in the Earth's atmosphere below which turbulent mixing dominates ^[6] 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. Molar mass, symbol M, is the Mass of one mole of a substance ( Chemical element or Chemical compound) Thus higher mass constituents, such as oxygen and nitrogen, fall off more quickly than lighter constituents such as helium, molecular hydrogen, and atomic hydrogen. Helium ( He) is a colorless odorless tasteless non-toxic Inert Monatomic Chemical Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 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. ^[7]

Density and mass

Earth's atmosphere from space.

Temperature and mass density against altitude from the NRLMSISE-00 standard atmosphere model. NRLMSISE-00 is an Empirical, global model of the Earth's atmosphere from ground to space

Main article: Density of air

The density of air at sea level is about 1. The density of air, ρ (Greek rho (air density is the mass per unit volume of Earth's atmosphere, and is a useful value in Aeronautics. 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 atmospheric density decreases as the altitude increases. This variation can be approximately modeled using the barometric formula. The barometric formula, sometimes called the exponential atmosphere or Isothermal Atmosphere, is a Formula used More sophisticated models are used by meteorologists and space agencies to predict weather and orbital decay of satellites.

The average mass of the atmosphere is about 5 quadrillion 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

The history of the Earth's atmosphere prior to one billion years ago is poorly understood and an active area of scientific research. The history of Earth covers approximately 46 billion years (4567000000 years from Earth ’s formation out of the Solar nebula to the present The following discussion presents a plausible scenario.

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. A chemical substance is a Material with a definite chemical composition. The original atmosphere was primarily helium and hydrogen. Helium ( He) is a colorless odorless tasteless non-toxic Inert Monatomic Chemical Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Heat from the still-molten crust, and the sun, plus a probably enhanced solar wind, dissipated this atmosphere. In Physics, heat, symbolized by Q, is Energy transferred from one body or system to another due to a difference in Temperature In Geology, a crust is the outermost solid shell of a planet or moon The solar wind is a Stream of charged particles&mdasha plasma &mdashthat are ejected from the upper atmosphere of the Sun.

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. Plate tectonics and hotspots Divergent plate boundaries At the Uses A Steam engine uses the expansion of steam in order to drive a Piston or Turbine to perform Mechanical work. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Ammonia is a compound with the formula N[[hydrogen H3]] It is normally encountered as a Gas with a characteristic pungent Odor This led to the early "second atmosphere", which was primarily carbon dioxide and water vapor, with some nitrogen but virtually no oxygen. General properties of water vapor Evaporation/sublimation Whenever a water molecule leaves a surface it is said to have evaporated Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the 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. This page is about the physical properties of gas as a state of matter In Chemistry, a carbonate is a salt or Ester of Carbonic acid. 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. ^[8] It is generally believed that the greenhouse effect, caused by high levels of carbon dioxide and methane, kept the Earth from freezing. The Greenhouse effect refers to the change in the Thermal equilibrium temperature of a planet or moon by the presence of an Atmosphere containing gas that absorbs Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. For freezing as a method of food preservation see Frozen food.

One of the earliest types of bacteria was the cyanobacteria. The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have Cyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of Bacteria that obtain their energy Fossil evidence indicates that bacteria shaped like these existed approximately 3. FOSSIL is a standard protocol for allowing serial communication for Telecommunications programs under the DOS Operating system. 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. The Oxygen Catastrophe was a massive environmental change believed to have happened during the Siderian period at the beginning of the Paleoproterozoic

Photosynthesising plants would later evolve and continue releasing oxygen and sequestering carbon dioxide. Photosynthesis is a Metabolic pathway that converts Light Energy into Chemical energy. eVolution is the third Album by eLDee, it was due to be released in 2008 Over time, excess carbon became locked in fossil fuels, sedimentary rocks (notably limestone), and animal shells. Fossil fuels or mineral fuels are fossil source Fuels that is Hydrocarbons found within the top layer of the Earth’s crust. Sedimentary rock is one of the three main rock types (the others being igneous and Metamorphic rock) Limestone is a Sedimentary rock composed largely of the Mineral Calcite ( Calcium carbonate: CaCO3 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. Photodissociation, photolysis, or photodecomposition is a Chemical reaction in which a Chemical compound is broken down by Photons

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. A chemical element is a type of Atom that is distinguished by its Atomic number; that is by the number of Protons in its nucleus. Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 An extinction event (also known as mass extinction; extinction-level event, ELE is a sharp decrease in the number of Species in a relatively short period With the appearance of an ozone layer (ozone is an allotrope of oxygen) lifeforms were better protected from ultraviolet radiation. The photochemical mechanisms that give rise to the ozone layer were worked out by the British physicist Sidney Chapman in 1930 Allotropy (Gr allos, other and tropos, manner is a behavior exhibited by certain Chemical elements these elements can exist in two or more different Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays This oxygen-nitrogen atmosphere is the "third atmosphere". 200 – 250 million years ago, up to 35% of the atmosphere was oxygen (as found in bubbles of ancient atmosphere were found in an amber).

This modern atmosphere has a composition which is enforced by oceanic blue-green algae as well as geological processes. Cyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of Bacteria that obtain their energy O₂ does not remain naturally free in an atmosphere, but tends to be consumed (by inorganic chemical reactions, and by animals, bacteria, and even land plants at night), and CO₂ tends to be produced by respiration and decomposition and oxidation of organic matter. In Animal physiology, respiration is the transport of Oxygen from the outside air to the cells within tissues and the transport of Carbon dioxide Decomposition (or spoilage) refers to the break down of tissue of a formerly living Organism into simpler forms of matter Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state 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). The Gaia hypothesis is an ecological Hypothesis proposing that the Biosphere and the physical components of the Earth ( Atmosphere

Air pollution

Before desulfurization filters were installed, the emissions from this power plant in New Mexico contained excessive amounts of sulfur dioxide. Flue gas desulfurization (FGD is the technology used for removing Sulfur dioxide (SO2 from the exhaust flue gases in power plants that New Mexico ( is a state located in the southwestern region of the United States of America.

Main article: Air pollution

Air pollution is a chemical, physical (e. Air pollution is the human introduction into the atmosphere of Chemicals Particulate matter, or Biological materials that cause harm or discomfort A chemical substance is a Material with a definite chemical composition. Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. g. particulate matter) or biological agent that modifies the natural characteristics of the atmosphere in an unwanted way. Particulates, alternatively referred to as particulate matter (PM or fine particles, are tiny particles of solid or liquid suspended in a gas 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. The stratosphere is the second major layer of Earth's atmosphere, just above the Troposphere, and below the Mesosphere. 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 Earth's The haloalkanes (also known as halogenoalkanes or alkyl halides) are a group of Chemical compounds consisting of Alkanes such as Methane An ecosystem is a natural unit consisting of all plants animals and micro-organisms( Biotic factors in an area functioning together with all of the non-living physical (

Worldwide air pollution is responsible for large numbers of deaths and cases of respiratory disease. Respiratory Disease is the term for Diseases of the Respiratory system. Enforced air quality standards, like the Clean Air Act in the United States, have reduced the presence of some pollutants. A Clean Air Act describes one of a number of pieces of legislation relating to the reduction of Smog and Air pollution in general While major stationary sources are often identified with air pollution, the greatest source of emissions is actually mobile sources, principally the automobile. A major stationary source is a source that emits more than a certain amount of a Pollutant as defined by the U 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. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. Fluorocarbons are chemical compounds that contain Carbon - Fluorine bonds The relatively low reactivity and high polarity of the carbon-fluorine bond imparts Global warming is the increase in the average measured temperature of the The Kyoto Protocol is a protocol to the international Framework Convention on Climate Change with the objective of reducing Greenhouse gases in an effort

See also

• Aerial perspective
• Air glow
• Airshed
• Atmosphere (for information on atmospheres in general)
• Atmospheric chemistry
• Atmospheric dispersion modeling
• Atmospheric electricity
• Atmospheric models
• Atmospheric Radiation Measurement (ARM) (in the US)
• Atmospheric stratification
• Aviation
• Biosphere
• Compressed air
• Global dimming
• Global warming
• Greenhouse effect
• Historical temperature record
• Hydrosphere
• Intergovernmental Panel on Climate Change (IPCC)
• Lithosphere
• Meteorology
• US Standard Atmosphere

References

External links

Another depiction of the layers of the atmosphere.

• NASA atmosphere models
• NASA's Earth Fact Sheet
• American Geophysical Union: Atmospheric Sciences
• Layers of the Atmosphere
• Answers to several questions of curious kids related to Air and Atmosphere
• The AMS Glossary of Meteorology
• Paul Crutzen Interview Free video of Paul Crutzen Nobel Laureate for his work on decomposition of ozone talking to Harry Kroto Nobel Laureate by the Vega Science Trust.
• Slides describing the Earth's modern atmosphere