Sentences with phrase «blackbody absorbers»

To build their device, the M.I.T. scientists used carbon nanotubes, which are extremely effective absorbers of sunlight; they approach theoretical «blackbody absorbers» that take in 100 percent of light shone on them.

Earlier in his paper, Postma (page 5) states: «If the source of light is constant, meaning it shines with the same unchanging brightness all the time, then the blackbody absorbing that light will warm up to some maximum temperature corresponding to the energy in the light, and then warm up no further.

The math presented so far merely establishes that if the earth were a blackbody absorbing 4 times less than the 1368 W / m ² that the sun provides, then its temperature, according to the Stefan - Boltzmann blackbody equation, would be about 278.6 K. Big deal.

Not exact matches

sigmaT ^ 4 is the upward blackbody radiation (based on stefan - boltzmann) at the surface, «a» is the albedo (reflectivity), so (1 - a) is the fraction of incident solar radiation that is absorbed by the planet.

This was the blackbody radiator fed with 240 W, that need to transfer 240W at equilibrium to a reflective blanket that only absorbs 10 % of the incident energy.

Furthermore, the wimpy «partial blackbody» CO2 absorbs and EMITS at a FIXED very - low - energy ~ 15 micron band, equivalent to a TRUE blackbody at 193K by Wien's Law.

In other words by imagining Earth as Blackbody [perfect absorber, emitter, and conductor of sunlight and heat] one create a uniform planetary temperature.

And Blackbody fictional construct is defined as body that can absorb all electromagnetic radiation.

So if total solar flux at Earth distance is 1360 watts per square meter, the blackbody would absorb all of this 1360 watts per square meter of this energy.

And almost everyone else assumes that all visible light is only absorbed and then once heated from this absorption of energy, it radiates as blackbody [it emits energy according to it's temperature].

Most solid and liquid surfaces are very close to a blackbody as emitter and absorber of LWIR (that's true even for the whitest snow).

And for the purpose of finding this blackbody temperature, some panel painted black [and absorbed all the other wavelengths] with well insulated back will reach this theoretical temperature.

It is, effectively, at the blackbody radiation temperature (and all molecules including N2 and O2 absorb and emit blackbody radiation — this seems to not be understood by many).

My understanding is that approximately 85 % of all photons in the Earth's blackbody spectrum that are also in the absorbtion spectrum of CO2 are already presently being absorbed at the present concentration of atmospheric CO2.

A room - temperature cavity resonator produces radiation at a wavelength associated with blackbody temperatures down around absolute zero which is absorbed by hot food to make it hotter.

It appears that you are somehow conflating this method of emulating a blackbody with Willis's though experiment where sunlight passes through his steel sphere without being absorbed.

To accept, without thought, that we can create something that absorbs more energy than a blackbody... I still don't understand that.

Now we realize that the outer part of our new smaller sphere must also absorb and radiate like a blackbody... and so on, all the way to the surface.

Ian Now we realize that the outer part of our new smaller sphere must also absorb and radiate like a blackbody... and so on, all the way to the surface.

By contrast, when you have the shell there, then some of the heat that the planet radiates (actually, in this simple example where the shell is a perfect blackbody, all of that heat) is absorbed by the shell which subsequently radiates part of it back to the planet.

Every blackbody above 0 K is both emitting and absorbing thermal radiation

What I'm saying is that a blackbody hung in the atmosphere through which 519W / m ^ 2 is steadily coursing would absorb all of it, not just what radiates to space.

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).

The earth is almost a perfect blackbody emitter in the mid & far - IR and since Kirchkoff's Law imply that the emissivity and absorptivity must be equal at each wavelength, the means that essentially all of the radiation that is incident on these objects is absorbed.

If CO2 absorbs at 15 micron, it also emits at 15 micron (not a blackbody distribution of all wavelengths based on atmospheric temperature).

This is confirmed when he later says (also page 5): «When a blackbody has reached thermal equilibrium, it can no longer absorb more light for heating and therefore has to re-emit just as much light - energy as it is absorbing.

Ira — regarding your summary comment 4) at May 8, 2011 at 7:51 pm my comment — NO, the atmosphere does NOT emit LWIR across a distribution of wavelengths like a blackbody, see my earlier comment at Dave in Delaware says: May 8, 2011 at 7:00 am Ira Glickstein, PhD says: «4) As I understand it, the ~ 15μm radiation from the Surface to the Atmosphere is absorbed by H2O and CO2 molecules which, when excited, bump into nitrogen and oxygen and other air molecules, and heat the air.

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.

Some clarity on a bit of terminology for new readers — a blackbody is a perfect emitter and absorber of radiation.

Supposing that the atmosphere is a blackbody, which is a fallacy, the absorbed power by the atmosphere must be 186 W / m ^ 2, not 324 W / m ^ 2 outcoming from the nothingness.

Now, the boundary conditions of radiational heat transfer theory are two states (1) a blackbody perfect emitter / absorber and (2) a perfect reflector which is a non emitter / non absorber.

For a start the definition of a blackbody (neutrino BB) Perry's Chemical Engineering Handbook (McGraw - Hill) states «The characteristic properties of a blackbody are that it absorbs all the radiation incident on its surface and that the quality and intensity of the radiation it emits are completely determined by its temperature» Note the word surface.