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Name: Unknown
Status: N/A
Age: N/A
Location: N/A
Country: N/A
Date: Around 1993


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?



Replies:
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.

Unknown

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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