Questions tagged [radiative-transfer]

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How does Collisional Ionization cause cooling?

I am trying to understand the different forms of radiative cooling such as recombination, collisional excitation, collisional ionization etc. In recombination and collisional excitation, the cooling ...
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Change of intensity along path element - plane-parallel geometry

How to derive this formula, please? Why is it true? $\mu$ is an emission coefficient
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272 views

Challenge: How can this meta-material be in thermal equilibrium?

The following simple ideal device comprises just two objects radiating at each other with a radiant concentrator in between. As far as I can tell, this device can't be in thermal equilibrium AND be at ...
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Brightness Temperature layered atmosphere

I'm trying to figure out how to apply the radiative transfer model to calculate the brightness temperature Tb in microwave (Rayleigh–Jeans approximation) considering atmosphere and no scattering. If I ...
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46 views

Radiative transfer equation for a three-level system

I am trying to derive the radiative transfer equation for a three-level system, which is supposed to be given by: $\frac{dI(\omega,x)}{dx}+N [\alpha\rho_{11}-\beta( \rho_{22}+\rho_{33})]I(\omega,x)=\...
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76 views

Calculating pressure and flux tensors in radiative astrophysics

I need to calculate the components of the radiative flux tensor and the pressure tensor, but I am having a little trouble figuring out what the integral should be. The flux is defined as $$F_v = 4{\pi}...
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112 views

Stationary equation of radiation transfer: Which one is correct?

I am currently studying radiative transfer. I have seen the stationary equation of radiative transfer written in two different ways: 1.$$\dfrac{\partial{I}(\mathbf{r}, \mathbf{s})}{\partial{s}} = - \...
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2answers
51 views

What is the solid angle $d\Omega$ in radiative transfer?

The Wikipedia article for radiative transfer gives the following definition: In terms of the spectral radiance, $I_{\nu }$, the energy flowing across an area element of area $da$, located at $\mathbf{...
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48 views

Difference between stationary and non-stationary radiative transfer?

I am currently studying radiative transfer. In researching this subject, I found that there is stationary radiative transfer and non-stationary radiative transfer. However, it is not clear what the ...
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How does radiation heating work at the fundamental level?

I was thinking something Let's consider radiation incident on a gas If it were a bunch of electrons in place of photons, then incident electrons would increase the kinetic energy of each and every ...
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1answer
42 views

What would be a beginner's book on radiative transfer?

I want to learn the basics of radiative transfer for my reasearch, which is on planetary sciences. I am looking for a book that would give me the basics of radiative transfer (the mathematics involved)...
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28 views

Temperature rise due to thermal radiation? [closed]

Consider a cylindrical metal rod of a certain diameter and length and a rectangular plastic plate of certain dimensions. The rod is suspended in air above the plate at a certain distance from the ...
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1answer
71 views

Melting plastic with radiant heat? [closed]

I want to melt a bed of plastic powder so that the powder bed once melted then cooled form a solid sheet of plastic. In order to melt the powder I thinking of passing a nichrome (Ni80/Cr20) wire over ...
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optical thickness of a supernova [closed]

I need to explain this question to a bunch of students tomorrow and I am not 100% sure how to solve it myself..Help would be much appreciated. The question is. If a Classical Nova ejects $10^{−5}$ ...
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328 views

Shouldn't $CO_2$ forcing depend on the surface temperature?

When I read about radiative forcing due to CO2 it says: "Radiative forcing is a measure of the influence a factor has in altering the balance of incoming and outgoing energy in the Earth-...
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How many scattering events happen in the atmosphere over 1 km?

In Vector Monte Carlo Atmospheric Radiative Transfer Simulations, they take a Stokes vector, let's say [1,1,0,0] and multiply it with a matrix, with elements close to 1. But if there are much ...
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238 views

Why the source function is equal to Planck function when we have a local thermodynamic equilibrium?

I understand that the source function $ S_λ $ for the special case of blackbody radiation is equal to the Planck function $B_λ $. However, in the broader case of a local thermodynamic equilibrium (...
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214 views

Heat transfer on Mars

SCENARIO: I have been tasked with finding the heat transfer across a composite wall on Mars. On the left of the wall there is air maintained at Earth atmospheric conditions and room temperature (101 ...