Emission may refer to:

Chemical products

* Emission of

air pollutant Air pollution is the presence of substances in the air that are harmful to humans, other living beings or the environment. Pollutants can be gases like ozone or nitrogen oxides or small particles like soot and dust. It affects both outdoor ...

s, notably: ** Flue gas, gas exiting to the atmosphere via a flue **

Exhaust gas Exhaust gas or flue gas is emitted as a result of the combustion of fuels such as natural gas, gasoline (petrol), diesel fuel, fuel oil, biodiesel blends, or coal. According to the type of engine, it is discharged into the atmosphere through ...

, flue gas generated by fuel combustion **

Emission of greenhouse gases Emission may refer to: Chemical products * Emission of air pollutants, notably: ** Flue gas, gas exiting to the atmosphere via a flue ** Exhaust gas, flue gas generated by fuel combustion ** Emission of greenhouse gases, which absorb and emit ...

, which absorb and emit radiant energy within the thermal infrared range *

Emission standard Emission standards are the legal requirements governing air pollutants released into the atmosphere. Emission standards set quantitative limits on the permissible amount of specific air pollutants that may be released from specific sources ov ...

s, limits on pollutants that can be released into the environment *

Emissions trading Emissions trading is a market-oriented approach to controlling pollution by providing economic incentives for reducing the emissions of pollutants. The concept is also known as cap and trade (CAT) or emissions trading scheme (ETS). One prominen ...

, a market-based approach to pollution control

Electromagnetic radiation

Emission spectrum The emission spectrum of a chemical element or chemical compound is the Spectrum (physical sciences), spectrum of frequencies of electromagnetic radiation emitted due to electrons making a atomic electron transition, transition from a high energ ...

, the spectrum of frequencies of electromagnetic radiation generated by molecular electrons making transitions to lower energy states *

Thermal emission Thermal radiation is electromagnetic radiation emitted by the thermal motion of particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation. The emission of energy arises from a combination of electro ...

, electromagnetic radiation generated by the thermal motion of particles in matter *

List of light sources This is a list of sources of light, the visible part of the electromagnetic spectrum. Light sources produce photons from another energy source, such as heat, chemical reactions, or conversion of mass or a different frequency of electromagnetic ener ...

, including both natural and artificial processes that emit light *

Emission (radiocommunications) Emission is the radiation or radio signal produced or emitted by a radio transmitting station.ITU Radio Regulations Radio regulation refers to the regulation and licensing of radio in international law, by individual governments, and by municipa ...

, a radio signal (usually modulated) emitted from a radio transmitter * Emission coefficient, a coefficient in the power output per unit time of an electromagnetic source *

Emission line A spectral line is a weaker or stronger region in an otherwise uniform and continuous spectrum. It may result from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used ...

, or "spectral line", a dark or bright line in an otherwise uniform and continuous spectrum *

Emission nebula An emission nebula is a nebula formed of ionized gases that emit light of various wavelengths. The most common source of ionization is high-energy ultraviolet photons emitted from a nearby hot star. Among the several different types of emission n ...

, a cloud of ionized gas emitting light of various colors *

Emission theory (relativity) Emission theory, also called emitter theory or ballistic theory of light, was a competing theory for the special theory of relativity, explaining the results of the Michelson–Morley experiment of 1887. Emission theories obey the principle of rela ...

, a competing theory for the special theory of relativity, explaining the results of the Michelson-Morley experiment *

Emission theory (vision) Emission theory or extramission theory (variants: extromission) or extromissionism is the proposal that visual perception is accomplished by eye beams emitted by the eyes. This theory has been replaced by '' intromission theory'' (or ''intromis ...

, the proposal that visual perception is accomplished by rays of light emitted by the eyes

Other uses

Thermionic emission Thermionic emission is the liberation of charged particles from a hot electrode whose thermal energy gives some particles enough kinetic energy to escape the material's surface. The particles, sometimes called ''thermions'' in early literature, a ...

, the flow of charged particles called thermions from a charged metal or a charged metal oxide surface, archaically known as the Edison effect *

Ejaculation Ejaculation is the discharge of semen (the ''ejaculate''; normally containing sperm) from the penis through the urethra. It is the final stage and natural objective of male sexual stimulation, and an essential component of natural conception. ...

, the ejection of semen from the penis; also, specifically: **

Nocturnal emission A wet dream, sex dream, or sleep orgasm, is a spontaneous occurrence of sexual arousal during sleep that includes ejaculation (nocturnal emission) and orgasm for a male, and vaginal lubrication and/or orgasm for a female. Context Nocturnal e ...

, ejaculation experienced during sleep *

Noise Noise is sound, chiefly unwanted, unintentional, or harmful sound considered unpleasant, loud, or disruptive to mental or hearing faculties. From a physics standpoint, there is no distinction between noise and desired sound, as both are vibrat ...

, emission *

Exhalation Exhalation (or expiration) is the flow of the breathing, breath out of an organism. In animals, it is the movement of air from the lungs out of the airways, to the external environment during breathing. This happens due to elastic properties of ...

of air, especially in the context of musical instruments

Chemical products

Electromagnetic radiation

Other uses

See also