Black Clothing in the Desert
We all know that white reflects heat while black absorbs most heat. In
the desert wearing a black robe would absorb more heat than a white one
(naturally), and wearing a black robe could increase temperatures inside
by about 6 degrees. Why do people wear black robes in the desert?
Some assumptions need validation:
1. Who says few/some/most/all people in the desert wear black robes -- or
have we been taking "Lawrence of Arabia" too seriously?
2. "Black" and "White" apply to the absorption / reflection of visible
light. It says nothing about the absorption / reflection of infrared, which
might be a more important factor.
3. It is assumed that the "black" and "white" fabric are the same type
material woven in the same way, etc. This point may not be correct. A black
loosely knit fabric may well be "cooler" than a tightly knit white fabric.
It would allow the fabric to "breathe" better.
4. Other issues than the coolest garment may be important. For example: Are
there religious or cultural reasons for wearing one color vs. another? If we
believe the newspaper and magazine photos, it would appear that most people
in the desert wear turbans rather than loose fitting headgear. Certainly
this practice is not consistent with keeping cool since most body heat is
lost from the head.
5. If the color of the dress is important, then certainly the color of the
skin is equally or more so. However -- although this is a generalization --
people living in hot climates tend to be dark skinned, and people who live
in cold climates tend to be light skinned.
This does not make sense, does it?
Need more data before any conclusions can be made about this inquiry.
I am going to guess...These things are usually not just for one reason.
First off some wear white , some wear black...even in the same tribe. Here
are some factors that will come into play:
Availability of color fabrics
Thickness of the fabric...layers
I recently saw a special on desert nomads of the African desert and some
wore white while other wore black. Also, I am not at all sure I would
accept the 6 degree estimate...It seems possible that the color will matter
much less in the multiple air layer that the robes assume. The outermost
layer would certainly absorb more heat but then it would have to be
conducted to through the inner layer(s). Here is a scenario. I wear a thin
tee shirt on a sunny day..if it is black I notice the difference form white.
If I then wear a tee shirt and a black shirt over it...it makes less of a
Peter Faletra Ph.D.
Office of Science
Department of Energy
Click here to return to the General Topics Archives
Update: June 2012