Sentences with phrase «emissivities over»

Prigent, C., F. Aires, and W.B. Rossow, 2006: Land surface microwave emissivities over the globe for a decade.

So, I 1) attached a surface mount thermocouple to the outside of the twinwall to measure the «actual» surface temperature, and 2) applied a roughly 1.5 by 1.5 inch piece of blue painters tape a few inches below the thermocouple — this is the often used technique of placing a patch of something with know emissivity over an unknown emissivity surface, and then measure the temperature on the known patch.

Redoing the final calculation of the earth's temperature with a better estimate of the emissivity over the range of terrestrial wavelengths yields a better estimate.

Not exact matches

And I # is emitted and absorbed by emission and absorption cross sections and emissivities and absorptivities that are equal for emission into a direction and absorption from that direction at the same location or over the same path length for the same frequency and polarization.

But emissivity of a rocky planet would certainly be less than 0.88 and so the temperature would be over 290K and thus there is actually cooling by greenhouse gases, as empirical data proves to be the case for water vapour.

Now I did use the word «averages over the planetary surface», but these obviously weighted averages - the effective temperature is weighted by the fourth power of itself, and the effective emissivity is weighted by the forth power of local temperature.

The only trick is knowing the emissivity of a surface (and whether the emissivity is constant over the wavelength range in question), but that doesn't really seem to be your difficulty.

We have been to some extent been glossing over this, but emissivity and absorptivity are functions of wavelength, and even direction.

You are forgetting that emissivity and absorptivity themselves are not constant over all wavelengths.

Phil says: «Where do you get your value of 0.2 emissivity from, what range of wavenumber is it for, why haven't you accounted for the variation of energy over the wavenumber range or the different absorption bands of H2O and CO2?»

The emissivity of the Earth is over 0.97 and a perfect black body is 1.0 so, for all intents and purposes, the Watts / m ^ 2 calculated by the Carleton spreadsheet based on Plank's Law may be off by only a small number of Watts / m ^ 2 and my main claim is that there are hundreds of Watts / m ^ 2 streaming down from the Atmosphere, so a few Watts here or there is a drop in a bucket.

The Earth Surface has an emissivity in the mid - and far - infrared that has been measured at over 0.98 for the oceans and over 0.95 for most land areas.

What is actually relevant in figuring out how much the earth is going to absorb is averaging the powers over the entire planet and what is relevant in figuring out how much it is going to radiate is averaging the temperature over the entire surface (actually T ^ 4... or, most technically, the emissivity * T ^ 4 but the emissivity in the mid - and far - IR is very close to 1 for most surfaces).

For calculating emission, it's more accurate to multiply the emissivity at each point by the Planck function at that point and sum over all wavelengths to get the total emission.

Microwave imagery must allow for variations in surface emissivity and can not act as a surrogate for air temperature over either snow - covered (Peterson et al., 2000) or sea - ice areas.

How do we know that the radiation absorption and emissivity of the oceans is not changing over multi-decadal scales which would affect the heat content of the oceans?

But for real world applications the amount that emissivity varies with temperature is small enough to not come into play for solid objects over terrestrial temperatures.