Glossary of Thermodynamic Terms

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absolute humidity
In an air-water system, the ratio of the mass of water vapor to the mass of dry air. [ kg water / kg dry air ]
2D6
absolute pressure Pressure measured relative to a vacuum (absolute zero pressure). [ atm, bar ] 1D3
absolute saturation
In a gas-vapor system, the ratio of the mass of vapor to the mass of vapor-free, non-condensable gas. [ kg vapor / kg dry gas ]
2D6
absolute temperature Absolute temperature is measured in either the SI scale of Kelvin or the American Engineering scale of Rankine. On an absolute temperature scale, the lowest possible temperature is 0.  Experimentally, the lowest achievable temperature is 0.000000002 K . [ K, R ] 1E10
absorptivity The ratio of incident radiation energy absorbed by a real surface to the radiation that would be absorbed if the surface were a blackbody. Absorptivity is a measure of how effectively the surface absorbs radiation. 4B23
acceleration work 4A20  ,  26
accumulation 5A2
adiabatic process A process in which no heat transfer across the system boundary occurs. 4B8 - 9
adiabatic compression 8C10  ,  11
adiabatic
compression		 accessible states 8C10  ,  11
air 2A2
air-standard assumptions 9E5
air-standard assumptions cold 9E11
American engineering units 1B4  ,  5  ,  7
ammonia 2C1
amorphous solids 2A7
Antoine equation 3E12
average velocity 5A5