Talk:Albedo/Archive 1

message: The reference given doesn’t work anymore (http://jeff.medkeff.com/astro/lunar/obs_tech/albedo.htm), I also found a reference that gives a different value of lunar albedo, of 0.12 instead of 0.072 (http://www.universetoday.com/guide-to-space/the-moon/moon-albedo/).    —Preceding unsigned comment added by Firstmatekevin (talk • contribs) 14:02, 4 July 2010 (UTC)
thread_title:  Lunar Albedo

message: The last sentence of the first paragraph is unclear; in comparison to land, do oceans typically have a higher or lower albedo, and do clouds contribute to higher albedo or to lower albedo?  —Preceding unsigned comment added by 75.85.89.204 (talk) 11:23, 20 December 2009 (UTC)
thread_title:  Terrestial vs. Ocean albedo unclear

message: I removed "(refs???)" from the end of the following sentence. Perhaps someone could actually find a decent reference for it.
:When Brazilian ranchers cut down dark, tropical rainforest trees to replace them with even darker soil in order to grow crops, the average temperature of the area allegedly increases by an average of about 3°C (5°F) year-round (refs???).
- Mark 05:25, 28 Jun 2004 (UTC)
replies: text: Certainly needs ref because, as I understand it, when tropical forest is removed it is often replaced quite rapidly by pasture, which corresponds to an increase in albedo.  The surface temperature increase is in response to the lower evaporation rate from pasture in spite of this albedo change. Deditos 11:24, 24 March 2006 (UTC)
thread_title:  Brazillian Ranchers 

message: Last bit, Kuwaiti Oil Fires: it seems contradictory, with the last sentence saying "impossible". Can someone who knows about this clear it up?
: (William M. Connolley 17:36, 26 Nov 2004 (UTC)
thread_title:  Kuwait oil fires 

message: I don't know where this article got the 0.31 Albedo figure of Earth.  Albedo 0.39 is what Kaufmann says; Pater and Lissauer say that Earth has a "bond albedo" of 0.29 and a "geometric albedo" of 0.37 source.  I changed the page to quote the albedo 0.39 figure, since that seems to be a reasonable number (and a really good album to boot). Samboy 08:18, 22 December 2005 (UTC)
replies: text: Sounds good to me. Every article needs more credible sources. Deco 09:19, 22 December 2005 (UTC)

text: I think both the bond albedo and geometric albedo should be given. I've usually seen the albedo given as 29 to 31 percent. Since Pater and Lissauer have both, I'll use them. -- Kjkolb 05:17, 5 January 2006 (UTC)
replies: text: First, I think bond albedo and geometric albedo should be defined and it should be stated which one is being used when a number is given or both should be given. -- Kjkolb 05:21, 5 January 2006 (UTC)
thread_title:  [[Albedo 0.39]] 

message: An automated Wikipedia link suggester has some possible wiki link suggestions for the Albedo article:
* Can link electromagnetic radiation: ...re of reflectivity of a surface or body. It is the ratio of electromagnetic radiation reflected to the amount incident upon it. The fraction, usu...
* Can link angle of incidence: ...s the spectrum of visible light. It also depends on the angle of incidence of the radiation: unqualified, normal incidence. Fresh snow...
* Can link weather station: ...thousands of weather stations across the world, the college weather station at Fairbanks, Alaska, is about 3°C (5°F) warmer tha... (link to section)
* Can link solar radiation: ...s especially marked during the late winter months, when solar radiation is greater. ... (link to section)
* Can link natural environment: ...itional zones. Part of the reason for this is the different natural environment of cities in tropical regions, e.g., there are more very da... (link to section)
* Can link carbon sequestration: ...ly warming) effect of albedo change and (cooling) effect of carbon sequestration on planting forests. They found that new forests in tropica... (link to section)
* Can link Climate models: ...ing from a minimum of near 0% to a maximum in the high 70s. Climate models have shown that if the whole earth were to be suddenly cove... (link to section)
* Can link greenhouse effect: ...mperature change due to an increase in the magnitude of the greenhouse effect, "all" we would need to do is increase the earth's overall ... (link to section)
* Can link indirect effect: ...direct (albedo) effect is generally to cool the planet; the indirect effect (the particles act as CCNs and thereby change cloud pro... (link to section)
Notes: The article text has not been changed in any way; Some of these suggestions may be wrong, some may be right.
Feedback: I like it, I hate it, Please don't link to — LinkBot 11:14, 1 Dec 2004 (UTC)
replies: text: Done .. added See also section with link to Global dimming Kgrr 14:24, 13 March 2007 (UTC)
thread_title:  Suggest 9 possible wiki links for [[Albedo]]. 

message: I have removed the following text pending the supply of a source for the statement:
:"Climate models have shown that if the whole Earth were to be suddenly covered by white clouds, the surface temperatures would drop to a value of about -150 °C (-240 °F). This model, though it is far from perfect, also predicts that to offset a 5 °C (9 °F) temperature change due to an increase in the magnitude of the greenhouse effect, "all" we would need to do is increase the Earth's overall albedo by about 12% by adding more white clouds."
This was marked with a "fact" template, which I think simply isn't enough.  We should rather remove unsourced statements of this level of significance and query them (as I do here) on the talk page. --Tony Sidaway 15:39, 2 July 2006 (UTC)
thread_title: "[[Climate model]]s have shown that if the whole Earth were to be suddenly covered by white clouds..." removed pending source

message: The albedo values for clouds given here differ from those given at cloud albedo.4.232.6.75 21:59, 12 August 2006 (UTC)
thread_title:  clouds 

message: The first line (on 12 Feb 2010) states:
"The albedo of an object is the extent to which it diffusely reflects light from light sources such as the Sun. It is therefore a more specific form of the term reflectivity. Albedo is defined as the ratio of diffusely reflected to incident electromagnetic radiation."
Restricting the description to "diffusely" implies that the specular reflection is ignored, which is not true.  Rather, the albedo measures the total reflected light ("exitance", to be precise, ref 1 below) summed over all directions, including both the specular component (generally brightest in the glint direction) and the diffuse component (generally seen at all angles, but not constant).  Unfortunately, there are multiple measures (definitions) of albedo, as described in the Astronomical Albedo section.  But I don't think any of them exclude all of the specular (glint) component, except to perhaps avoid the peak of the glint.
I propose the following:
 "The albedo of an object is a measure of how strongly it reflects light from light sources such as the Sun. It is therefore a more specific form of the term reflectivity. Albedo is defined as the ratio of total-reflected to incident electromagnetic radiation."
 (1) Gutman, G.,"A Simple Method for Estimating Monthly Mean Albedo of Land Surfaces From AVHRR Data", Journal of Applied Meteorology, 1988, vol = 27, pp 973-988.
Chonny (talk) 20:49, 12 February 2010 (UTC)
thread_title:  First Line (again) 

message: Okay, the Fairbanks section says:
:According to the National Climatic Data Center's GHCN 2 data, which is composed of 30-year smoothed climatic means for thousands of weather stations across the world, the college weather station at Fairbanks, Alaska, is about 3 °C (5 °F) warmer than the airport at Fairbanks, partly because of drainage patterns but also largely because of the lower albedo at the college resulting from a higher concentration of spruce trees and therefore less open snowy ground to reflect the heat back into space. Neunke and Kukla have shown that this difference is especially marked during the late winter months, when solar radiation is greater.
..but I read once that some climatologists said that if they plant about 10,000 trees in the ever-sunny steaming-hot San Fernando Valley of Los Angeles, that it could lower the average temperature of the Valley by several degrees, as the Valley's concrete sidewalks are reflecting the sunlight and heating up the air for several meters above the surface. So- which is right? or, is it that the trees will provide shade, heating up themselves to provide cooler air at the surface? I'm confused. - Eric 00:10, 25 December 2006 (UTC)
thread_title:  Fairbanks vs. Van Nuys 

message: Sure the Albedo is highest if the light is reflected by objects that are white?  --pizza1512 Talk Autograph 06:28, 30 April 2007 (UTC)
thread_title:  Reflection 

message: I've searched the web for specific references to the albedo effects of large-scale deserts, e.g. Sahara, on a hunch that the high albedo effect of such deserts may be a significant balance of Earth's temperature control mechanism. Suspiciously, such references are unavailable - nobody seems to have addressed that point.
I read something years ago concerning Gaia Theory and "Daisyworld", and a search brought up http://www.schumachercollege.org.uk/articles/college-articles/stephan/fromgaiatheory.html
In place of bright daisies, think deserts.
As we increasingly burn more fossil fuels we are heating the environment, with such heat being transferred globally, increasing the size of those deserts. Desertification is seen as bad, but I wonder if it is the only mechanism that currently we have to prevent runaway global warming? Deserts may become increasingly important as reflectors of heat back to space, to maintain temperature balance. Those countries (typically economically poor) may be supported economically by the world community, in the same way as is being proposed through the "carbon cap and trade" idea. 
  
Much is being made of the value of using solar power farms as a green way of obtaining heat for our use, but surely they are yet more "black daisies" that will add to global warming.
Basically, we are hungry for energy, and are releasing it from within the Earth as fossil fuel, and will be trapping it on its arrival from the Sun (as solar energy farms). After we've finished with it, every bit of that energy ends up in the environment at large. We need to find a way of gathering that waste energy for redistribution. 
Fractain 17:43, 1 May 2007 (UTC)
thread_title:  Desert Albedo 

message: this is my first wikipedia article edit, so don't mind the mess I make of formatting...
several places this article cites temperatures that are innaccurate in some sense, because 3 degrees Celsius is simply not the same as 5.4 degrees fahrenheit.
unless there is something I am completely missing.
who wrote this?
Raging thunder (talk) 16:06, 11 December 2007 (UTC)
replies: text: You have made the familiar error of confusing absolute and relative temperatures. 3 oC is not 5.4 oF. But a difference of 3 oC is a difference of 5.4 oF. Personally I'd just rid of all the oF's... 16:09, 11 December 2007 (UTC)
thread_title:  temperatures? 

message: I wrote this article as a mock research paper in high school and then put it on Wikipedia in 2001 as a prank:   I'm sorry for letting it sit here this long; I really didn't think about it after I did it, and it took me five years to remember that I had ever even edited the Albedo article, much less created it.  I remembered when I came here looking for information on albedo for a real research paper, and reading through the article I realized I was reading some of my own words.  So I removed most of it, but apparently either i missed some or the edits were restored.  So this time I'm really cleaning up.  Note: the info I'm removing isn't necessarily wrong; it's just that the original paper was only a mock paper, to teach us how to write research papers, so the factual accuracy of the information wasn't really important.  I remember myself just skimming through some books on the subject and jotting down various notes.   Once again, I apologize for vandalizing Wikipedia and for taking seven years to confess to it and clean up after myself.  If you look at my recent contributions, you can see that I have ~2000 good faith edits and no bad ones.  <FONT COLOR="#800000"><B>Soap</B></FONT> Talk/Contributions 17:05, 19 September 2008 (UTC)
thread_title:  I removed some old vandalism (of my own) 

message: I think the geoengineering material should be removed. It is outside the scope of albedo as a physical concept and quantity, and while relevant geoengineering articles can link to this page, I don't think it warrants its own section here, and perhaps not even to be mentioned. Awickert (talk) 17:30, 31 January 2009 (UTC)
replies: text: Removed. If re-added, I suggest that it is through more info on the albedo of different substances, through the current structure. Awickert (talk) 22:50, 1 February 2009 (UTC)
thread_title:  Geoengineering 

message: I believe that the definition of albedo is the fraction of all sunlight reflected (all wavelengths not just visible wavelengths as stated in the article)
Hke33ly (talk) 22:48, 13 April 2009 (UTC)
thread_title:  definition 

message: A surface can have an albedo even if it has never been exposed to sunlight.  So why mention the sun in its definition?--Singularitarian (talk) 10:08, 2 September 2009 (UTC)
replies: text: True.  But--mostly albedo is used in astronomy and climatology, so it makes sense that the sun would be in the definition.  Also, the just because an object has not been exposed to sunlight does not mean it will not reflect a certain way if it is ever exposed to sunlight.  Oh, and since we and everything around us is made of star stuff, everything has at one point been exposed to starlight, if you want to be pedantic.  Not trying to be difficult here; just think it would be wrong to define albedo without sunlight.  --Turboguppy (talk) 14:32, 2 November 2013 (UTC)
thread_title:  Not just the sun 

message: This article seems to be written from the perspective of a climatologist or an astronomer.  However, albedo is an important concept in computer graphics and computer vision as well.  It seems the article should be revised to account for these perspectives.--Singularitarian (talk) 10:04, 12 September 2009 (UTC)
replies: text: The subject of albedo seems to be hard to find on the net as relates to computers--most references I found to it are related to using it exactly as described in this article--that is controlling lighting in a three-dimensional space, with regards to reflectivity of light sources.  A small section might be added to address this, but hardly seems necessary as a computer programmer looking up albedo is likely to already know why it is needed, and need it for the reasons described; however, the point is valid that albedo is a concept in computer work, and deserves a mention.--Turboguppy (talk) 14:22, 2 November 2013 (UTC)
thread_title:  Not just climatology and astronomy 

message: Key for understanding concept of green roofs to reduce urban heat islands and slow global warming is concept of high-albedo construction materials.  
Need a section here to point to from roofing or a new section on high-albedo roofing & paving materials, etc.
Mitigation via high albedo materials: 
See, e.g., http://en.wikipedia.org/wiki/Urban_heat_island#Mitigation
Relation to Global Warming: 
http://en.wikipedia.org/wiki/Urban_heat_island#Relation_to_global_warming 
Ocdcntx (talk) 15:41, 16 February 2010 (UTC)
thread_title:  Needs mention of high-albedo roofing materials 

message: Do the values given refer to some "reference" spectrum of white light or to sunlight (which is 50% IR)? This needs to be clarified. According to the "Percentiles" section of our page Planck's Law, 50% of sunlight is infrared at wavelengths > 711 nm. Therefore, the difference between solar and visible albedos becomes very large. In the case of snow, the near-IR albedo is roughly 50% less than the visible, thus a visible albedo of 90% would be a total solar albedo of less than 70%, representing a 200% "increase" (!!!!) in absorbed energy. I wouldn't exactly call this negligible...
129.2.46.178 (talk) 00:58, 4 June 2010 (UTC)
thread_title:  Visible vs. solar spectrum 

message: Section 3.5, the article says there is higher albedo from water early and late in the day, but calls this a high angle.  The highest angle is normally (no pun intended) when the sun is directly overhead.  The high albedo is at low angles, when the sun is near the horizon.  The article is very unclear on these points.   Ladarzak (talk) 05:57, 18 February 2012 (UTC)
thread_title:  Low and High Angles 

message: What is it?  — Preceding unsigned comment added by Goatbar (talk • contribs) 18:25, 2 May 2016 (UTC)
thread_title:  Blue sky albedo