Sentences with phrase «absorptivity of»

Absorptivity of any material MUST to be measured, not deduced.

I have demonstrated that my calculations of total emissivity and total absorptivity of carbon dioxide are based on the experimental / observational work of scientists.

It is well documented that the earth's reflectivity (albedo) is approximately 0.3 which leads to absorptivity of 0.7.

If Nasif wants to go and derive the absorptivity of a surface, in this case the earth, he is free to do that.

I referred you back to my original calculation because the end result -LRB--18.3 C) was for an earth absorbing with absorptivity of 0.7 across solar wavelengths and an emissivity of 1.0 across terrestrial wavelengths.

I do know what the total absorptivity of the earth system is.

Then he adds this grandiose statement: «@All... I have demonstrated that my calculations of total emissivity and total absorptivity of carbon dioxide are based on the experimental / observational work of scientists.

If you're a physicist, as you say, derive a formula from the above equation and then calculate the real absorptivity of the Earth.

Although the initial debate was on the total emissivity and absorptivity of the carbon dioxide and the effect of overlapping, Neutrino decided to create a confusion so the issue of the overlapping absorption bands was forgotten.

In an atmosphere there is backradiation contributing to the incident T on the absorptivity of the surface; however this incident T from backradiation is in fact from the surface; in this circumstance calculating emissivity from the surface is a measure of the backradiation returning as absorptivity incident T.

(Their calculation used: Absorptivity of 0.69, Emissivity of 1.0, Incident flux at earth of 1368W / m ^ 2 and absorption as the product of Absorptivity and Incident.)

Therefore, to assume that the absorptivity of the earth's surface for solar radiation is equal to the emissivity of the earth's surface is a huge mistake.

No matter what absorptive - radiative band you take; the emissivity and absorptivity of the carbon dioxide doesn't change.

I used an absorptivity of 0.1905 for a hemispherical gas mass of radius L = 3600m.

But S. Manabe (personal communication) points out that Arrhenius got reasonable results in large part because he underestimated the absorptivity of water vapor, and thus underestimated the crucial influence of water vapor feedback on the heat balance, a feedback kept within bounds in the real world by the upward convection of heat.

The equivalent for CO2 requires a product term PcL of 0.0004 * 900 * (4 * 3.281) ft.atm giving a CO2 absorptivity of 0.2 absorbing 84Wm - 2 of land LWIR in 4m.

I tried Googling «water absorption spectrum pH» as I suspected there may be pH - related changes in the absorptivity of water (there are).

R Stevenson says: May 22, 2011 at 9:07 am This is based on the increase in CO2 concentration needed to make the gas as effective as water vapour in absorbing LWIR ie based on equivalence: For a product term PwL of 0.0231 * (4 * 3.281) ft.atm a water vapour absorptivity of o. 2 absorbs 84Wm - 2 of land LWIR in 4m.

2) The albedo of the Earth Surface is 12 % based on absorptivity of visual and near - visual Solar radiation (what we have been calling short - wave).

This is based on the increase in CO2 concentration needed to make the gas as effective as water vapour in absorbing LWIR ie based on equivalence: For a product term PwL of 0.0231 * (4 * 3.281) ft.atm a water vapour absorptivity of o. 2 absorbs 84Wm - 2 of land LWIR in 4m.

Further to our recent posts concerning the above and Hottel; 0.2 (or 0.193) is the emissivity / absorptivity of CO2 in the atmosphere to the extinction point of 3600m for dry air.

The one thing that you and Postma are leaving out is what I said in my last post... that the average height of 5 km is determined by the IR - absorptivity of the atmosphere, i.e., by the greenhouse gases in the atmosphere and clouds.

In my method I calculate the absorptivity of a hemispherical mass of gas (dry air for CO2 alone) of radius L (L = extinction distance) using graphs developed by Hottel and Mangelsdorf which can be found in Heat Trnsmission by McAdams.

«ε» refers to the emissivity of the hot object, «a» refers to the absorptivity of the hot object, it is nowhere implied that «the absorbtivity and emissivity of the surroundings be the same as that of the emitting object»

For example, common glass has an absorptivity of close to 0.0 at short - wave but about 1.0 at long - wave.

I calculate the emissivity / absorptivity of water vapour again using Hottel's emissivity v absolute T graphs.

The emissivity and absorptivity of the ocean are set to 1, there are no ocean currents, the atmosphere doesn't heat up and cool down with the ocean surface, the solar radiation value doesn't change through the year, the top layer was 5 mm not 1μm, the cooler skin layer was not modeled, a number of isothermal layers is unphysical compared with the real ocean of continuously varying temperatures..

So, if Willis wants to use an emissivity of 1 at the long infrared, then he would have to use an absorptivity of 1 at the long infrared as well.

Take the absorptivity of the earth to be 0.7.

The emissivity and absorptivity of small molecules like CO2 and H2O follow the structure of their line absorption spectrum.

It obviously depends on the absorptivity of your target at the frequency in question.

What matters in energy transfer via light is two things: The intensity of the light, that is, the power per square centimeter (more properly the Poynting vector of the light as the power incident on any surface is the flux of the Poynting vector through the surface, correcting for surface geometry and the direction of the light); the absorptivity of the material in the wavelength chosen.

For example, considering the pressure and temperature, the water vapor's total absorptivity is 0.4, while the total absorptivity of carbon dioxide is merely 0.0017.

The total load of thermal energy transferred from the surface to the air by conduction - convection at the boundary layer is ~ 68.7 W * s. Therefore, I don't find any «strong» absorptivity of carbon dioxide at 15 μm.

From experimental evidence we know that the absorptivity of a body is not affected by the amount of incident radiation, or by any imbalance between the body and its environment.

The absorptivity of carbon dioxide in the infrared is a physical property of the gas and can not be changed.

The short - and long - wave absorptivities of the most important greenhouse gases water vapour, carbon dioxide, methane and ozone are derived from line - by - line calculations based on the HITRAN08 - databasis and are integrated in the model.

The short - and long - wave absorptivities of the most important greenhouse gases water vapour, carbon dioxide, methane and ozone are derived from line - by - line calculations based on the HITRAN08 - databasis and are integrated in the model.

Introduction Key diagrams on the Earth's energy budget depicts an exchange of energy between the surface and the atmosphere and their subsystems considering each system as if they were blackbodies with emissivities and absorptivities of 100 % 1, 2.

Not exact matches

Investigating the thermophysical properties of materials in concentrated sunlight, including thermal expansion, thermal conductivity and diffusivity, specific heat, mechanical properties, and spectral emissivity and absorptivity

This is because the fundamentals of thermal radiation from an isolated slab: emissivity, absorptivity, transmissivity, are related by emissivity = absorptivity = (1 — transmissivity) where transmissivity = exp -LRB-- TAU)(neglecting directionality).

The short answer is that it does — but the longer answer also notes that the absorptivity and emissivity of a given substance or object are directly related.

That heat must be dissipated to space, and CO2 (which does not absorb in the UV or visible range), adds to the emissivity of the stratosphere at the warmed temperature, while adding much less to the absorptivity.

For other reasons, at LTE, the transmission (of a given type of photon) is the same in a pair of opposite directions, so in the absence of scattering, emissivity and absorptivity must each be the same for opposite directions across the same path of material, and thus they will be the same for absorption of photons from a direction and emission of photons into the opposite direction.

I.absorbed / I.incident = absorptivity; I.absorbed = I.emitted; I.incident = B.emitted (because they have the same brightness temperature, where B.emitted is what would be emitted by a blackbody, and is what would be in equilibrium with matter at that temperature), emissivity = I.emitted / B.emitted; therefore, given that absorptivity is independent of incident intensity but is fixed for that material at that temperature at LTE, and the emitted intensity is also independent of incident intensity but is fixed for that material at that temperature, emissivity (into a direction) = absorptivity (from a direction).

d (absorptivity) / ds = (absorption cross section density) * exp -LRB-- s * (absorption cross section density)-RRB- = absorption cross section density * transmitted fraction over distance s = fraction of intensity from s = 0 that reaches s and is absorbed per distance ds;

For those who want to check out the physics, read up the statistical thermodynamics which leads to Kirchhoff; s law of radiation and realise that «Prevost exchange energy» is needed to connect the IR density of states in the two objects in radiative equilibrium and maintain absorptivity = emissivity.

The important point is that thermodynamics considerations allow us to see that absorptivity = emissivity (both as a function of wavelength), and experimental considerations allow us to extend the results to non-equilibrium conditions.

Much attention has been given to the CO2 absorption band at 15 microns because this absorption peak has high absorptivity placed in the far - IR region, and the paramitization of its effects have been comparably easy to quantify (Fomichev et al., 1993; Fomichev & Turner, 1998; Kiehl & Briegleb, 1991).

And for those who wish to understand my stance, there can be no present CO2 - AGW because if you look in the Metallurgical Literature, Hoyt C. Hottell, replicated later by Leckner, showed experimentally that the absorptivity / emissivity of CO2 in air levels off at ~ 200 ppmV in an infinite physical optical path.