emissivity
Noun
Meaning
Tendency to emission; comparative facility of emission, or rate at which emission takes place, as of heat from the surface of a heated body.
Source: Webster's dictionarySynonyms
Phrases with the word
Examples
However, by definition, the radiation from a gray body is simply proportional to that of a black body at the same temperature, so its emissivity does not depend upon frequency (or, equivalently, wavelength).
A source with lower emissivity independent of frequency often is referred to as a gray body.
But added parameters are needed to determine local emissivity and albedo and address the factors that move energy about the earth.
During the night, the atmosphere cools somewhat, but not greatly, because its emissivity is low.
For example, it easily determines the effect on average earth temperature of changes in solar constant or change of albedo or effective earth emissivity.
For that reason, incorrect selection of emissivity will give inaccurate results when using infrared cameras and pyrometers.