At 09:00 PM Monday 9/20/04, Dan Minette wrote:
The sun radiates photons from its surface at ~4000K via blackbody radiation.
Nit: closer to 6000K.
They peak around yellow, in the visiable spectrum.
Nit: around 550nm, in the yellow-green portion of the visible spectrum.
The earth receives these photons as energy in a relatively low entropy form. Its in (roughly) thermal equilibrium, so it must radiate the same amount of energy out. But, since it is at, roughly, 300K, it radiates ~10x the number of photons each of which has ~10% of the energy of the sun's photons.
Nit: 5%. (Wein's Law: peak wavelength is proportional to 1/T, Planck's Law: E = hc/wavelength, therefore the energy of the photons at the peak wavelength is proportional to T, and the effective temperature of the Sun (5770 K) is about 20x the average temperature of the Earth (288 K).)
-- Ronn! :)
"Earth is the cradle of humanity, but one cannot remain in the cradle forever." -- Konstantin E. Tsiolkovskiy
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