Heat Absorption vs. Color

Question: Why does the color Black absorb heat and White reflect heat?  What 
are the physical properties behind this fact?  I have seen some Arabs where 
Black robes in the desert -- this seems to defeat the purpose.  Do they wear 
them because black protects more against harmful UV rays?
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First of all I have no idea why some Arabs wear black robes in 
the desert.  It seems counter-productive...but oh well, different strokes for 
different folks.  Anyway, the color that we observe (i.e.  the color of a 
particular object) is really only the light that is reflected from that 
object.  For example, a red ball appears red because when white light strikes 
it, all of the light is absorbed except for the red frequencies/wavelengths 
which are reflected into our eyes.  A white light is made up of all visible 
(and invisible) wavelengths all mixed together.  So an object that appears 
white, is reflecting all of the incident wavelengths and absorbing nothing (or 
very little).  A black object, on the other hand is absorbing all of the 
incident wavelengths (along with all of their energies) which causes it to 
heat up.  That is why snow does not melt in cold weather even when the sun is 
falling directly on it.  All of the incident light energy is reflected away 
and none (or very little) is absorbed.
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Up-date July 2001

The explanation I heard for this is that the clothes themselves are
very loose (rather like Roman togas). The extra heat caused by the
black colour causes increased upward convection of the air between
the cloth and their body. This additional air circulation actually aids in 
evaporation of persiration and thus results in better cooling.

Robert Wilson
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