Sentences with phrase «emissivity across»

An ideal GB has uniform emissivity across all wavelengths, from gamma through visible and infrared all the way to radio.

The above math shows that if the earth, without an atmosphere, is placed in a 1368W / m ^ 2 flux (which is the solar flux at the distance of 1 earth radius from the sun) then it will have a temperature of 278.6 K (or 5.4 C) if the earth was a BB or even an ideal GB (uniform emissivity across all wavelengths).

GB's are bodies that have uniform emissivity across all wavelengths.

The earth does not have uniform emissivity across every wavelength.

Not exact matches

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.

This is in addition to there being a much higher partial pressure of water vapor (up to 2.5 %) in the atmosphere than that of CO2 (400ppm which varies with height) It should also be noted that the absorptivity and emissivity of liquid water is close to unity across the full range of wavelength from UV to microwaves.

which is, indeed, the Stefan - Boltzmann formula for net power radiatively transferred to / from a hot reservoir at temperature to a cold reservoir at temperature across a vacuum between to facing plates of area and emissivity.

However, as an educational tool, we can calculate the results for a grey atmosphere — this means that the emissivity is assumed to be constant across all wavelengths.

Across the wavelengths where the earth is absorbing solar radiation (0.2μm - 4μm) the earth has approximately an emissivity of 0.7.

The «flaw» was that the emissivity of the earth was pegged at 0.7 across all wavelengths.

The 5.4 C result (line 20) is for an earth with uniform emissivity of 0.7 across both spectrums.

B) How does» Across the wavelengths where the earth is emitting its own radiation (4μm - 40μm) it has an emissivity close to 1.»

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.

Five temperatures across the globe averaged (272 +285 +271 +301 +297) / 5 = 282.2 K so radiation to space ignoring emissivities is 5.67E - 08 • 282.2 ²² = 359.59 Wm - 2 right?