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