Earth's atmosphere has no definite boundary, slowly becoming thinner and fading into outer space. Three-quarters of the atmosphere's mass is contained within the first 11 km of the surface. This lowest layer is called the troposphere. Energy from the Sun heats this layer, and the surface below, causing expansion of the air. This lower-density air then rises and is replaced by cooler, higher-density air. The result is atmospheric circulation that drives the weather and climate through redistribution of thermal energy. The primary atmospheric circulation bands consist of the trade winds in the equatorial region below 30° latitude and the westerlies in the mid-latitudes between 30° and 60°.


NN 2 dinitrogen
Nitrogen gas was inert enough that Antoine Lavoisier referred to it as "mephitic air" or azote, from the Greek word άζωτικός (azotikos), "no life". In an atmosphere of pure nitrogen, animals died and flames were extinguished.


Ccarbonaceouscarbon atom
Proven sources of natural gas are about 175 cubic metres (containing about 105 gigatonnes of carbon), but studies estimate another 900 cubic metres of "unconventional" deposits such as shale gas, representing about 540 gigatonnes of carbon. Carbon is also found in methane hydrates in polar regions and under the seas. Various estimates put this carbon between 500, 2500 Gt, or 3,000 Gt. In the past, quantities of hydrocarbons were greater. According to one source, in the period from 1751 to 2008 about 347 gigatonnes of carbon were released as carbon dioxide to the atmosphere from burning of fossil fuels.

Carbon dioxide

CO 2 CO2carbon dioxide (CO 2 )
Carbon dioxide can be obtained by distillation from air, but the method is inefficient. Industrially, carbon dioxide is predominantly an unrecovered waste product, produced by several methods which may be practiced at various scales. The combustion of all carbon-based fuels, such as methane (natural gas), petroleum distillates (gasoline, diesel, kerosene, propane), coal, wood and generic organic matter produces carbon dioxide and, except in the case of pure carbon, water.

Greenhouse gas

greenhouse gasescarbon emissionsgreenhouse gas emissions
The size of the indirect effect can depend strongly on where and when the gas is emitted. Methane has indirect effects in addition to forming. The main chemical that reacts with methane in the atmosphere is the hydroxyl radical (OH), thus more methane means that the concentration of OH goes down. Effectively, methane increases its own atmospheric lifetime and therefore its overall radiative effect. The oxidation of methane can produce both ozone and water; and is a major source of water vapor in the normally dry stratosphere. CO and NMVOCs produce when they are oxidized. They remove OH from the atmosphere, and this leads to higher concentrations of methane.


Hesuperfluid heliumhelium II
This radiogenic helium is trapped with natural gas in concentrations as great as 7% by volume, from which it is extracted commercially by a low-temperature separation process called fractional distillation. Previously, terrestrial helium—a non-renewable resource, because once released into the atmosphere it readily escapes into space—was thought to be in increasingly short supply. However, recent studies suggest that helium produced deep in the earth by radioactive decay can collect in natural gas reserves in larger than expected quantities, in some cases having been released by volcanic activity.


Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or compound molecules made from a variety of atoms (e.g. carbon dioxide). A gas mixture would contain a variety of pure gases much like the air. What distinguishes a gas from liquids and solids is the vast separation of the individual gas particles. This separation usually makes a colorless gas invisible to the human observer.


HH 2 hydrogen gas
Hydrogen is often produced using natural gas, which involves the removal of hydrogen from hydrocarbons at very high temperatures, with about 95% of hydrogen production coming from steam reforming around year 2000. Commercial bulk hydrogen is usually produced by the steam reforming of natural gas. At high temperatures (1000–1400 K, 700–1100 °C or 1300–2000 °F), steam (water vapor) reacts with methane to yield carbon monoxide and. This reaction is favored at low pressures but is nonetheless conducted at high pressures (2.0 MPa, 20 atm or 600 inHg).

Compressed natural gas

CNGcompressed natural gas (CNG)natural gas
Compressed natural gas (CNG) (methane stored at high pressure) is a fuel which can be used in place of gasoline, diesel fuel and propane/LPG. CNG combustion produces fewer undesirable gases than the aforementioned fuels. In comparison to other fuels, natural gas poses less of a threat in the event of a spill, because it is lighter than air and disperses quickly when released. Biomethane – cleaned-up biogas from anaerobic digestion or landfills – can be used. CNG is made by compressing natural gas, (which is mainly composed of methane, CH 4 ), to less than 1 percent of the volume it occupies at standard atmospheric pressure.

Gas flare

flaringflareflare stack
Therefore, to the extent that gas flares convert methane to CO 2 before it is released into the atmosphere, they reduce the amount of global warming that would otherwise occur. A knockout drum to remove any oil or water from the relieved gases. A water seal drum to prevent any flashback of the flame from the top of the flare stack. An alternative gas recovery system for use during partial plant startups and shutdowns as well as other times when required. The recovered gas is routed into the fuel gas system of the overall industrial plant. A steam injection system to provide an external momentum force used for efficient mixing of air with the relieved gas, which promotes smokeless burning.


crude oiloilcrude
Under surface pressure and temperature conditions, lighter hydrocarbons methane, ethane, propane and butane exist as gases, while pentane and heavier hydrocarbons are in the form of liquids or solids. However, in an underground oil reservoir the proportions of gas, liquid, and solid depend on subsurface conditions and on the phase diagram of the petroleum mixture. An oil well produces predominantly crude oil, with some natural gas dissolved in it. Because the pressure is lower at the surface than underground, some of the gas will come out of solution and be recovered (or burned) as associated gas or solution gas. A gas well produces predominantly natural gas.

Carbon monoxide

COcarbon monoxide (CO)carbon monoxide poisoning
Because natural sources of carbon monoxide are so variable from year to year, it is difficult to accurately measure natural emissions of the gas. Carbon monoxide has an indirect effect on radiative forcing by elevating concentrations of direct greenhouse gases, including methane and tropospheric ozone. CO can react chemically with other atmospheric constituents (primarily the hydroxyl radical, OH . ) that would otherwise destroy methane. Through natural processes in the atmosphere, it is eventually oxidized to carbon dioxide and ozone. Carbon monoxide is both short-lived in the atmosphere (with an average lifetime of about one to two months) and spatially variable in concentration.

Combined cycle

CCGTcombined cycle gas turbinecombined-cycle
Often in gas turbine designs part of the compressed air flow bypasses the burner and is used to cool the turbine blades. Supplementary firing raises the temperature of the exhaust gas from 800 to 900 degree Celsius. Relatively high flue gas temperature raises the condition of steam (84 bar, 525 degree Celsius) thereby improving the efficiency of steam cycle. Combined cycle plants are usually powered by natural gas, although fuel oil, synthesis gas or other fuels can be used. The supplementary fuel may be natural gas, fuel oil, or coal. Biofuels can also be used.


OO 2 molecular oxygen
Submarines, submersibles and atmospheric diving suits usually operate at normal atmospheric pressure. Breathing air is scrubbed of carbon dioxide by chemical extraction and oxygen is replaced to maintain a constant partial pressure. Ambient pressure divers breathe air or gas mixtures with an oxygen fraction suited to the operating depth. Pure or nearly pure use in diving at pressures higher than atmospheric is usually limited to rebreathers, or decompression at relatively shallow depths (~6 meters depth, or less), or medical treatment in recompression chambers at pressures up to 2.8 bar, where acute oxygen toxicity can be managed without the risk of drowning.

Atmosphere (unit)

Atmospheric pressure. International Standard Atmosphere.

Global warming

climate changeglobal climate changeanthropogenic climate change
On Earth, an atmosphere containing naturally occurring amounts of greenhouse gases causes air temperature near the surface to be warmer by about 33 C-change than it would be in their absence. Without the Earth's atmosphere, the Earth's average temperature would be well below the freezing temperature of water. The major greenhouse gases are water vapour, which causes about 36–70% of the greenhouse effect; carbon dioxide (CO 2 ), which causes 9–26%; methane (CH 4 ), which causes 4–9%; and ozone (O 3 ), which causes 3–7%.

Water vapor

water vapourvaporevaporation
Under typical atmospheric conditions, water vapor is continuously generated by evaporation and removed by condensation. It is less dense than air and triggers convection currents that can lead to clouds. Being a component of Earth's hydrosphere and hydrologic cycle, it is particularly abundant in Earth's atmosphere where it is also a potent greenhouse gas along with other gases such as carbon dioxide and methane. Use of water vapor, as steam, has been important to humans for cooking and as a major component in energy production and transport systems since the industrial revolution.

Hydrogen sulfide

hydrogen sulphideH 2 SH2S
Hydrogen sulfide is commonly found in raw natural gas and biogas. It is typically removed by amine gas treating technologies. In such processes, the hydrogen sulfide is first converted to an ammonium salt, whereas the natural gas is unaffected. :RNH 2 + H 2 S RNH + SH − The bisulfide anion is subsequently regenerated by heating of the amine sulfide solution. Hydrogen sulfide generated in this process is typically converted to elemental sulfur using the Claus Process. Hydrogen sulfide is a highly toxic and flammable gas (flammable range: 4.3–46%). Being heavier than air, it tends to accumulate at the bottom of poorly ventilated spaces.


H 2 Oliquid wateraqueous
evaporation from oceans and other water bodies into the air and transpiration from land plants and animals into air. precipitation, from water vapor condensing from the air and falling to earth or ocean. runoff from the land usually reaching the sea. Atmosphere of the Sun: in detectable trace amounts. Atmosphere of Mercury: 3.4%, and large amounts of water in Mercury's exosphere. Atmosphere of Venus: 0.002%. Earth's atmosphere: ≈0.40% over full atmosphere, typically 1–4% at surface; as well as that of the Moon in trace amounts. Atmosphere of Mars: 0.03%. Atmosphere of Ceres. Atmosphere of Jupiter: 0.0004% – in ices only; and that of its moon Europa.


Today, almost all elemental sulfur is produced as a byproduct of removing sulfur-containing contaminants from natural gas and petroleum. The greatest commercial use of the element is the production of sulfuric acid for sulfate and phosphate fertilizers, and other chemical processes. The element sulfur is used in matches, insecticides, and fungicides. Many sulfur compounds are odoriferous, and the smells of odorized natural gas, skunk scent, grapefruit, and garlic are due to organosulfur compounds. Hydrogen sulfide gives the characteristic odor to rotting eggs and other biological processes.

Diesel fuel

dieseldiesel oilgas oil
Other sources include biomass, animal fat, biogas, natural gas, and coal liquefaction. Petroleum diesel, also called petrodiesel, or fossil diesel is the most common type of diesel fuel. It is produced from the fractional distillation of crude oil between 200 C and 350 C at atmospheric pressure, resulting in a mixture of carbon chains that typically contain between 9 and 25 carbon atoms per molecule. Synthetic diesel can be produced from any carbonaceous material, including biomass, biogas, natural gas, coal and many others. The raw material is gasified into synthesis gas, which after purification is converted by the Fischer–Tropsch process to a synthetic diesel.


NH 3 anhydrous ammonialiquid ammonia
As of 2012 the global production of ammonia produced from natural gas using the steam reforming process was 72 percent.


SiberianEastern SiberiaWestern Siberia
The frozen peat bogs in this region may hold billions of tons of methane gas, which may be released into the atmosphere. Methane is a greenhouse gas 22 times more powerful than carbon dioxide. In 2008, a research expedition for the American Geophysical Union detected levels of methane up to 100 times above normal in the atmosphere above the Siberian Arctic, likely the result of methane clathrates being released through holes in a frozen 'lid' of seabed permafrost, around the outfall of the Lena River and the area between the Laptev Sea and East Siberian Sea. There are at least three different types of faces in Siberian tribes & ethnicities.

Global warming potential

global-warming potentialGWP22 times more powerful
., CO 2, CH 4, and N 2 O). For those gases, the relative radiative forcing will depend upon abundance and hence upon the future scenario adopted. Since all GWP calculations are a comparison to CO 2 which is non-linear, all GWP values are affected. Assuming otherwise as is done above will lead to lower GWPs for other gases than a more detailed approach would.


C 2 H 6 dimethyldicarbon hexahydride
After methane, ethane is the second-largest component of natural gas. Natural gas from different gas fields varies in ethane content from less than 1% to more than 6% by volume. Prior to the 1960s, ethane and larger molecules were typically not separated from the methane component of natural gas, but simply burnt along with the methane as a fuel. Today, ethane is an important petrochemical feedstock and is separated from the other components of natural gas in most well-developed gas fields. Ethane can also be separated from petroleum gas, a mixture of gaseous hydrocarbons produced as a byproduct of petroleum refining. Economics of building and running processing plants can change, however.