Grey atmosphere
The grey atmosphere (or gray) is a useful set of approximations made for radiative transfer applications in studies of stellar atmospheres (atmospheres of stars) based on the simplified notion that the absorption coefficient α ν {\displaystyle \alpha _{\nu }} of matter within a star's atmosphere is constant—that is, unchanging—for all frequencies of the star's incident radiation. == Application == The grey atmosphere approximation is the primary method astronomers use to determine the temperature and basic radiative properties of astronomical objects, including planets with atmospheres, the Sun, other stars, and interstellar clouds of gas and dust.