What does 'albedo' mean?
We have been compelled to create this page out of a sense of public duty and a measure of embarrassment.
As people who go through our server logs with a fine toothcomb, we have noticed that a fair number of hits on this site - from Google and other search engines - are from people wanting to know the meaning of 'albedo'.Out of a sense of public duty, and some embarrassment - after all, these are page hits we don't really deserve - we thought we might as well answer the question.
In fact, as you can see from the graphic, 'albedo' is simply a measure of the reflectivity of a surface. It is most commonly used in astronomy or astrophysics but can, in theory, be applied in any discipline.
Although one can vaguely refer to a surface having a high or low albedo - be more or less reflective - it does have an exact mathematical definition. The albedo of a surface is simply the percentage of radiation, expressed as a decimal, in a given waveband reflected by the surface.
Now, the default waveband for albedo is visible light (it is possible, though rare, to refer to infrared or ultraviolet albedos), so when Vangelis produced that well known album Albedo 0.39, he was referring to the fact that the Earth reflects, on average, 39 percent of all visible light impinging on it.
Sure - it's a cloudy old planet, but we do have to say that there are many figures quoted for Earth's albedo. One thing is certain, and that is that it is higher than 0.3 and less than 0.4 - our guess is that seasonal factors and even climatic change may underly these disparities.
Origins of albedo
We haven't traced the exact origins of 'albedo', but it is not an ancient term. Merriam-Webster and other sources trace it to 1859, which suggests that it was coined by an astronomer of the time. (If anyone can pin it down more exactly, please mail us).
It does seem clear that the term has been derived from Latin 'albus' meaning 'white'. This goes some way to explaining why it was chosen by us as a company name. (No - there is no sinister racist plot here, don't worry).
Apart from the fact that we dig astrophysics, and that reflection is a worthwhile human activity, not merely a physical process, the two co-founders of Albedo Systems both have first names deriving from the Irish Gaelic for 'white' or 'fair'. So we just had to have that name...
Finally, for a lot more useful information, including figures on the various albedos of different solar system objects, try this:
http://www.google.com/search?q=define:albedo
