Talk:Effective temperature

message: The first sentence of the article says "The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation."  In the case of a star the motivation for this definition is clear, as is the definition itself.  In the case of a planet however the motivation is less clear since planets take as well as give, and the definition is even less clear as a result.
In particular a planet emits two kinds of radiation, insolation reflected by water vapor, snow, etc, at a short wavelength and thermal emission at a much longer wavelength, around 23 times longer in the case of Earth.  Reading between the lines of the formula for planets one deduces that reflected insolation is not counted as part of the planet's emission.  This still leaves unanswered various questions, e.g. the status of insolation trapped in the atmosphere during the day and radiated away at night before it has reached the surface.
Does there exist an unproblematic interpretation of the first sentence of the article in the case of planets?  --Vaughan Pratt (talk) 07:14, 8 November 2009 (UTC)
replies: text: The reflected part is counted in the Albedo; I would assume that radiation absorbed in the atmosphere and later reradiated is treated the same as radiation absorbed anywhere else and reradiated later -- some planets are nothing but atmosphere after all.  Dicklyon (talk) 17:03, 8 November 2009 (UTC)
thread_title: Question about the first and second sentences

message: 155.68.106.162 you made this change http://en.wikipedia.org/w/index.php?title=Effective_temperature&curid=1460629&diff=480622467&oldid=480620530 I suggest it is not clear what is your source and/or justfication for it. Care to explain? Also you are currently anonymous, it is a lot easier for other contributors if you give yourself a name, thanking you in advance. --Damorbel (talk) 06:33, 8 March 2012 (UTC)
replies: text: What exactly isn't clear? I used a more general form which makes thing more clear i would assume. The new equations show the relations to emissivity, absorption area and emission area that the previous equations didn't. sorry for the delay. you can call me Jack. 71.59.83.12 (talk) 06:27, 15 March 2012 (UTC)
replies: text: Jack, for one thing, the emissivity estimate of 0.5 might give a better way to estimate the temperature of the Earth, but it's not an "effective temperature"; see the definition again.  Your edit seems to be confusing different things, plus it contains unverifiable data (see WP:V).  The stuff about areas is interesting, too, but where's a source that supports what you say about it?  Dicklyon (talk) 06:36, 15 March 2012 (UTC)
replies: text: I see what you mean. Chapter 5 section 1 of Quantitative Astronomy by Thomas Swihart uses the equations I used, he calls it Surface Temperature not Effective Temperature. My mistake. I think these equations are useful though and should be incorporated, perhaps we could add it in a section below or an entirely new article? Jack  155.68.165.137 (talk) 22:59, 19 March 2012 (UTC)
thread_title:  Effective temperature? 

message: Doing a bit of algebra, I obtain for the theoretical temperature of the planet:
:T = \left(\frac{A_{\rm abs}}{A_{\rm rad}}\frac{1-a}{\varepsilon}\right)^{1/4}
\left(\frac{R}{D}\right)^{1/2}T_{\rm eff},
where T_{\rm eff} and R are the Sun's temperature and radius, respectively.  Any objections to its insertion after the already present equation,
T = \left (\frac{A_{\rm abs}}{A_{\rm rad}} \frac{L (1-a)}{4 \pi \sigma \varepsilon D^2} \right )^{\tfrac{1}{4}}  ?
(This is much easier to calculate, since the Sun's temperature is easier to look up than its Luminosity.  Also, the units are simpler to handle.) --guyvan52 (talk) 01:08, 22 February 2014 (UTC)
replies: text: Also, I am confused by the capital and lower case letters for albedo.  Is A=a? If so, we need to replace A by a (since capital A is already used as area).--guyvan52 (talk) 01:23, 22 February 2014 (UTC)
replies: text: If you read the section fully you'll find that the capital A's are the areas of absorption and radiation Jhmadden (talk) 00:25, 15 December 2014 (UTC)
replies: text: okay we have two sections about the effective temp of a planet in one article! I see your point with this equation, it is useful. I'd like to merge the two sections and write them more clearly as well as make the different cases more clear Lambert sphere, tidal lock, etc. and include separate equations for each instead of just using writing. Very commonly people just assume lambert sphere and set the ratio of A's to 1/4 and also no atmosphere and set epsilon to 1 getting the simpler equation so I'll keep the most general form and talk about the limiting cases and provide those equations.  sometime in the next few weeks i'll make these changes. sorry for the delay Jhmadden (talk) 23:25, 30 November 2015 (UTC)
thread_title:  Proposed insertion of additional equation for planetary Temperature. 

message: I think Planetary equilibrium temperature and the "Planet" chapter of Effective temperature are actually the same topic.
Also it seems that equilibrium temperature and effective temperature are (at least in this context) the same thing.
In my opinion the two articles should either be merged, or at least visible cross referenced.
What's currently not good is that "equilibrium" and "effective" temperature are misleadingly defined like they would be different, while actually they are defined by the same formulas (and planetary equilibrium temperature is the same as effective temperature... for planets); in the formulas, the luminosity and albedo are notated (slightly) differently but everything else is identical, like two different people worked independently on two different articles which actually are about the same subject:
http://en.wikipedia.org/wiki/Effective_temperature#Planet 
vs
http://en.wikipedia.org/wiki/Planetary_equilibrium_temperature#Detailed_derivation_of_the_planetary_equilibrium_temperature
-Paul- (talk) 10:43, 22 October 2014 (UTC)
replies: text: This article is here to stay as the temperature in the elementary formula \mathcal{F}=\sigma T_{\rm eff}^4 is defined (by most textbooks) as the 'effective' temperature not the equilibrium temperature so any use of this formula is using the effective temperature whether its for a planet or star. If a student googles to find this info they will search what their textbook says and it will say 'effective temperature'. I'd really like to clean up this article as it is a mess right now (2 sections for planets!). I'll have some time to write things more coherently in the next few weeks. I'll post my revisions in the talk first. Jhmadden (talk) 23:53, 30 November 2015 (UTC)
thread_title:  Merge needed ?

message: The intro states: 
"When the star's or planet's net emissivity in the relevant wavelength band is less than unity (less than that of a black body), the actual temperature of the body will be higher than the effective temperature. "
This is totally incorrect on many levels; lower emissivity does not dictate a higher temperature, whatsoever.  Net emissivity in a "relevant wavelength" has even less to do with any "actual temperature," even in the most idealized scenario.   
Also, clearly, even in the most basic idealized scenario, what is relevant is both the specific nature of both EM spectrum and the spectrally-dependent emissivity where ever absorption and emission can occur.    Wikibearwithme (talk) 18:22, 6 January 2016 (UTC)
thread_title:  totally incorrect basic physics

message: Teff Hα vs Teff color is not noted in text. Would be nice to have it noted. arxiv.org, Porto de Mello et al.: Spectroscopic and photometric survey of solar twinsTelecine Guy 19:55, 19 July 2016 (UTC)
thread_title: Teff Hα vs Teff color

message: Twice I came across the phrase: "radiation spread over the surface of a sphere of radius D". From the context it is clear that reference is made to an emitting surface, not a receiving surface. But the words "spread over the surface" suggest to me that the surface is receiving.
I propose the phrase be changed to "radiation originating from the surface of a sphere of radius D". Any objections or suggestions?Redav (talk) 04:17, 20 January 2019 (UTC)
replies: text: The wording is a bit sparse, I agree. The sphere being referenced in either case is the imaginary surface of a sphere with radius equal to the distance between the source and the receiver. Not the radius of the source. For example the energy a star (of radius R) that hits a planet (of radius r) is related to how that energy is distributed on a sphere of radius D, the distance between the planet and star.  Jhmadden (talk) 19:38, 23 September 2019 (UTC)
thread_title:  Radiation ''spread over'' the surface of a sphere of radius D? 

message: What does one mean by surface temperature exactly? The common notion of temperature is associated with the mean motion of particles and molecules and is measured in kelvins (K). This is a thermodynamic temperature. Satellite measurements of temperature using a bolometer, say, gives a radiation temperature which is at best an estimate of the thermodynamic temperature. Are bolometer measurements sufficiently unique to be described as a separate temperature scale? Should the observations be given in "langleys" instead of kelvins to avoid confusion? It might be noted that variations in surface conditions affect heating and observations. Are "langleys" inherently as accurate as kelvins? How might such considerations affect our perception of climate change? Is there an element of deception in using bolometric temperatures for the monitoring and recording temperature changes over time? Or for recording record highs and lows? Jbergquist (talk) 11:54, 25 August 2021 (UTC)
thread_title:  Kelvins vs "Langleys"