# Tag Info

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Yes, the amount of radiation (i.e. power) would decrease $N^4$ times, since the whole geometry of the system does not change, only the power emitted by the sun. But the temperature of the earth would decrease only $N$ times, since the ratio of the temperatures remains equal - again because of the unchanged geometry. The earth radiates a power proportional ...

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Background The specific intensity or brightness, $I_{\nu}$, is defined as: $$I_{\nu} = \frac{ dE }{ dA \ dt \ d\Omega \ d\nu } \tag{1}$$ where $\nu$ is the frequency, $dE$ the differential energy, $dA$ the differential area, $dt$ the differential time, $d\Omega$ the differential solid angle, and $d\nu$ the differential frequency. We can define a net flux ...

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I'm not familiar with the math, but am wondering if the 4 should be a 2 instead, (for hemisphere). The Moon's day is about 13.5 of our days, so at its highest the lit side and dark side of the Moon can vary up to 500 degrees F, from about 250F on the lit side to about -250F on the dark side. I would suggest that our atmosphere - which is literally mass ...

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For what it's worth, lg310's seem to run a little cooler than gxb300's, at least on my roof. See also http://dx.doi.org/10.1016/j.egypro.2014.02.148 but read Table 4 carefully. The differences seem to be small.

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To understand the origin of black body radiation, which is what every material body with a temperature T has been measured to emit, one has to go to quantum statistical mechanics. Atoms and molecules, to start with, in any ensemble, interact with the electromagnetic radiation. At that level, the processes are quantum mechanical. In quantum mechanics the ...

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An arbitrary speed is tricky, but the ultra relativistic case is easier. If you look at this What's the max speed a man-made satellite can travel in space before its circuitry stopped working? SE answer, I noted that the *specific intensity * (in W m$^{-2}$ sr$^{-1}$ Hz$^{-1}$ of the CMB radiation is boosted by a factor $z^3$, where $z$ is the usual ...

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Here's a thought experiment, together with why it will not work. This is a very hand-waving argument, for which I apologise (I would add it as a comment but it is too long). Imagine a black-body source which completely surrounds some object. That object will clearly end up at the same temperature as the source (for the sake of concreteness the source ...

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You propose to use a color filter to change the effective color temperature of a blackbody source. This however never allows to reach higher light intensity, or more exactly radiance, which is the decisive factor for the maximum temperatures higher than the source. I do not know the exact definition of a passive device. Provided the device can not use the ...

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Thermal output radiation from the small sphere is given by the Stefan-Boltzman law, power = A σ T^4 = σ 4π r^2 T^4 but of course the NET radiated power is more interesting; output minus input Net_power = σ 4π r^2 (T_inner ^4 - T_outer^4) The important thing to remember, is that the area of that small sphere is part of the scale of its thermal radiation, ...

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