Sentences with phrase «blackbody emission»

If you accept Kirchoff's law for the moment, that tells you that the emission is the absorption coefficient times the very same Planck function B (nu, T) that governs blackbody emission.

First, he used a blackbody at 100C (basically, a pot of boiling water) as the source for his infrared radiation, and measured the transmission relative to the full blackbody emission of the source.

To be clear, the Hottel average is across the entire blackbody emission for that temperature.

Well, if it's blackbody emission, yes.

Low cloud cover provides a perfect blackbody emission curve when looking up, no CO2 emission lines, no methane line no H20 lines, a perfect blackbody.

But Claes Johnson's paper is only about spontaneous blackbody emission, not induced emission as in a laser.

Request for clarification from a retired engineer: when it's said that methane is N times the greenhouse gas that CO2 is, is that purely taking into account their absorption spectra relative to the blackbody emission from the surface, or does it take into account saturation as well, since methane constitutes a much smaller percentage wrt CO2?

Given that the effective blackbody emission must be constant (and allowing for a small movement in the effective radiating level), an increasing gradient must therefore lead to cooling far above this level.

The Stefan - Boltzmann is NOT an appropriate equation to perform the calculations used in climate science — ONLY Planck's equation completely describes blackbody emissions.

Not exact matches

Blackbody radiation was an extension clarifying further details about heat, emission and temperature.

The work is an estimate of the global average based on a single - column, time - average model of the atmosphere and surface (with some approximations — e.g. the surface is not truly a perfect blackbody in the LW (long - wave) portion of the spectrum (the wavelengths dominated by terrestrial / atmospheric emission, as opposed to SW radiation, dominated by solar radiation), but it can give you a pretty good idea of things (fig 1 shows a spectrum of radiation to space); there is also some comparison to actual measurements.

Refraction, specifically the real component of refraction n (describes bending of rays, wavelength changes relative to a vacuum, affects blackbody fluxes and intensities — as opposed to the imaginary component, which is related to absorption and emission) is relatively unimportant to shaping radiant fluxes through the atmosphere on Earth (except on the small scale processes where it (along with difraction, reflection) gives rise to scattering, particularly of solar radiation — in that case, the effect on the larger scale can be described by scattering properties, the emergent behavior).

So while, in the isothermal blackbody surface approximation, if the starting surface temperature is 288 K and we know the OLR is reduced from surface emission by 150 W / m2 via GHE, we know that removing all greenhouse agents will have a TOA forcing of -150 W / m2, (and some forcing at the tropopause, etc.) which will cool the surface temperature to about 255 K at equilibrium, absent non-Planck feedbacks.

For a small amount of absorption, the emission upward and downward would be about the same, so if the upward (spectral) flux from below the layer were more than 2 * the (average) blackbody value for the layer temperature (s), the OLR at TOA would be reduced more than the net upward flux at the base of the layer, decreasing CO2 TOA forcing more than CO2 forcing at the base, thus increasing the cooling of the base.

Emissivity = proportion of emission with reference to a blackbody (it's a ratio) Emission = emissivity x what a blackbody would emit at that temperature (it's an absolute value)

It seems to me that any layer from the surface to the highest limits of the atmosphere is radiating some roughly blackbody looking spectrum corresponding to its own Temperature; and much of that spectrum exits directly to space (assuming cloudless skies for the moment) with a spectrum corresponding to the emission temperature of that surface; but now with holes in it from absorption by GHG molecules or the atmospheric gases themselves.

The infrared radiation hangs around longer than it would have done, some being absorbed by matter, causing heating, which causes higher re-emission (the blackbody spectrum of the whole Earth's emissions moves slightly to a higher energy - temperature profile, in order to balance out the radiation budget of the Earth).

After all, it makes perfect sense that something that is nearly a blackbody at a temperature of about 15 C will emit only 50 W / m ^ 2 of emission (gross)... at least once you repeal a few laws of physics that were never much use to us anyway!

whereF is radiant - energy flux at the emitting surface; εis emissivity, set at 1 for a blackbody that absorbs and emits all irradiance reaching its emitting surface (by Kirchhoff's law of radiative transfer, absorption and emission are equal and simultaneous), 0 for a whitebody that reflects all irradiance, and (0, 1) for a graybody that partly absorbs / emits and partly reflects; and σ ≈ 5.67 x 10 — 8 is the Stefan - Boltzmann constant.

This is called the Planck feedback because it is fundamentally due to the Planck blackbody radiation law (warmer temperatures = higher emission).

I pull this number out of my mind meaning that the N2 - O2 spectrum corresponds to a blackbody with 100um peak, which would correspond to a body at about 40K with total emission of 45mW / m2.

It is a simple application of the Stefan - Boltzman equation for blackbody radiation that gives an increase in radiative emissions from Earth, until it once again equals the radiation coming into the Earth.