from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. The ratio of the radiation emitted by a surface to the radiation emitted by a blackbody at the same temperature.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. The energy-emitting propensity of a surface, usually measured at a specific wavelength.

from the GNU version of the Collaborative International Dictionary of English

  • n. Tendency to emission; comparative facility of emission, or rate at which emission takes place

from The Century Dictionary and Cyclopedia

  • n. Emissive or radiating power.
  • n. Specifically A physical constant by means of which the power of radiation of a body is quantitatively expressed.


Sorry, no etymologies found.


  • The amount of blackbody energy emitted is strictly and solely a function of the thermal temperature of the substance, mitigated by the characteristic of the substance called emissivity (which can, as you say, by frequency dependent).


  • Buy double-or triple-pane models, designated Energy Star with a "low E" (for "emissivity") coating.

    Save Energy—And Money

  • Perhaps the most interesting realization is that the concept of reciprocity applies to the ‘kludge’ factor called emissivity – the correction value that permits a greybody to be modeled with planck’s law and stefan’s law – applies to the atmosphere.

    Gerry North's Suggested Reading on Climate Models « Climate Audit

  • Materials commonly used in urban areas for pavement and roofs, such as emissivity than the surrounding rural areas. rss feed

  • I used a black body approximation to the earth’s emissivity, that is, an emissivity of 1.

    USCCSP: Temperature Trends in the Lower Atmosphere « Climate Audit

  • The roof is made of "low emissivity" or "cool" roof materials, so it reflects sunlight rather than absorbing its heat.

    In Bethesda, a home built to have a net-zero carbon footprint

  • Builders can achieve significantly higher rates of energy efficiency with only a few minor changes: plugging air leaks in the building envelope so that the owner will not be heating or cooling the great outdoors; sealing the ducts that deliver heating and air conditioning with mastic glue instead of tape, which can disintegrate; installing better windows with a low-emissivity coating; and adding more insulation to basements, crawl spaces, walls and attics.

    Housewatch: Building green without losing greenbacks

  • One of the largest manufacturers, Velux, offers triple-coated low-emissivity glass, which helps with energy efficiency.

    Skylights can add magic to a house, but installation is everything

  • In #3 you can omit discussion of emissivity and Stefan Boltzmann constants, and leave them out of the parenthetical term.

    Another Try

  • Finally, changes in the emissivity of the sun have taken place over billions of years, but there have been shorter-term variations that occurred over decades, centuries, and millennia.

    Arctic climate variability prior to 100 years BP

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