Quote:
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Originally Posted by cbacba
Quote:
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Originally Posted by Bored Wombat
Quote:
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Originally Posted by cbacba
P = epsilon * sigma * T^4
epsilon = emissivity
sigma = stefan's constant
T = absolute temperature
P = power radiated / unit area (W/m^2)
do simple example - double P
and double double epsilon
what value do you have to change T by for the result to balance?
HINT = T doesn't have to change at all in the example.
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Increasing the concentration of CO 2 from 0.028% to 0.038% does not double epsilon for the atmosphere. In fact it makes nearly no difference at all in epsilon for the atmosphere. |
Evidently, you haven't yet grasped that epsilon is not a one value number often used as an engineering simplification but rather a very complicated function of wavelength. |
Only if you are interested in power per unit area as a function of wavelength. Since we are talking about global warming, the relevant value is the total power over all wavelengths in W/m2.
And since temperature and the Stefan-Boltzmann constant are both scalars, the relevant epsilon would be the total epsilon over all wavelengths ... that is to say, the one value number often used as an engineering simplification.
Otherwise your own equation P= ε.σ.T^4 doesn't work. A scalar cannot equal a "very complicated function of wavelength" times two scalars, can it?