Emission

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 radiant energy within the thermal infrared range
Emission standards, limits on pollutants that can be released into the environment
Emissions trading, a market-based approach to pollution control

Emission spectrum, the spectrum of frequencies of electromagnetic radiation generated by molecular electrons making transitions to lower energy states
Thermal emission, electromagnetic radiation generated by the thermal motion of particles in matter
List of light sources, including both natural and artificial processes that emit light
Emission (radiocommunications), 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, or "spectral line", a dark or bright line in an otherwise uniform and continuous spectrum
Emission nebula, a cloud of ionized gas emitting light of various colors
Emission theory (relativity), a competing theory for the special theory of relativity, explaining the results of the Michelson-Morley experiment
Emission theory (vision), the proposal that visual perception is accomplished by rays of light emitted by the eyes

Thermionic emission, the flow of charged particles from a charged metal or a charged metal oxide surface, archaically known as the Edison effect
Field emission, the releasing of electrons from a material due to effects of a strong electrostatic field
Ejaculation, the ejection of semen from the penis; also, specifically:
- Nocturnal emission, ejaculation experienced during sleep
Noise, emission
Exhalation of air, especially in the context of musical instruments