Wearing black in a desert

  1. I understand that the color black is a really good emitter of heat, but why do people in the desert (especially in the middle east) wear loose fitting black robes? Would not the black color absorb more heat than it emits during the daytime hours?
     
  2. jcsd
  3. It's probably a bad idea to wear black robes but there must be some reason.

    All I can say is that most of the pictures I have seen show people wearing light colors.
     
  4. Here is a pic
     

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  5. Dadface

    Dadface 2,069
    Gold Member

    The absorbed heat sets up convection currents.Warm air rises and leaves the top of the clothing and this is replaced by cooler air which enters the bottom of the clothing.It's like a solar powered fan.
     
  6. If you have seen the movie 'Lawrence of Arabia' you will have noticed how cool Omar
    Shariff appears in black, while Lawrence (Peter O'toole) would look like a dork.....so in the movie he
    wore the white of the another tribe....

    Actually, the above is a weak attempt at humor....and you can see actual photos here
    where it seems Lawrence also wore black, unlike the movie:
    http://en.wikipedia.org/wiki/Lawrence_of_Arabia

    I wonder if black was considered more menacing in appearance....lots of warrier garb was based on intimidation....Or maybe that color material was more readily available? Or did that show how tough groups like the Bedouin were to their peers?

    Dadface may be right about convection, but since the clothing appears generally snug at the neck and shoulders it would seem to trap more heat than it releases. Why snugly wrap the head in black?
     
    Last edited: Feb 11, 2012
  7. Well, who knows...there are cold deserts around the world, too, you know? Not all are burning hot or sunny...maybe this picture is of a desert way far from the equator and high altitude...
     
  8. ...or early in the morning
     
  9. Dadface

    Dadface 2,069
    Gold Member

    I was replying to the first post where kjamha stated that the clothing was "loose fitting".Now ,having had a look at the picture, I agree that the clothing shown appears to be "snug".My guess is that the clothing is adjustable and can be tightened up when the temperature drops.Also,extra and or different items of clothing are probably worn depending on the temperature.
     
  10. cepheid

    cepheid 5,194
    Staff Emeritus
    Science Advisor
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    Black things tend to emit just as much as they absorb (a good absorber is a good emitter). What effect this has on cooling the body, I do not know, but I did find this article:

    http://www.straightdope.com/columns/read/1886/does-black-clothing-keep-you-cooler

    Comments???
     
  11. Just think how crappy you would look wearing white after working in dirt all day. I can tell you from personal experience, the black fabric hides a lot of "smelly" dirt.
     
  12. cepheid, the article was great - So it seems if it is a breezy hot day, it would be better to wear black clothing vs. white. Would anyone out there refute this article? It does seem counter intuitive.
     
  13. BruceW

    BruceW 3,544
    Homework Helper

    cepheid's right that black clothing would absorb and emit heat better than white clothing. (Hence the term 'blackbody radiation'). I'm going to go out on a limb and say that the human body will always have a greater temperature than the surroundings (since the body generates its own heat), so in this case it is good to wear black clothing because it will allow heat to flow easier, thereby cooling the person down. Just an educated guess, but who knows, it might be right :)

    But I don't know why it would be useful to wear snug clothing... I would have guessed loose-fitting is better, so that air can circulate easier, carrying away heat from the body.
     
  14. Bruce...where are you from? Not from any hot place, I presume. I am from the Sonoran desert and my summers included daily temperatures higher than body temperature. In celcius body temperature is 37.5; my summers included temperatures from 38 to 48...one time I even remember a 52.
     
  15. Sounds like the article has the answer.....

    When crossing the great Nefu (Negev)desert in the movie, the warrior group and Lawrence rested during one brutally hot section...but oddly did not loosen their garb...instead they were shown holding sticks vertically or one end stuck in the sand...... with white material 'tent's formed above their heads for shade....
     
  16. cepheid

    cepheid 5,194
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    Off topic, but I'll chime in with agreement here. I'm from a very cold place as you can see from my profile. But I do remember landing at Dubai airport at midnight one night at the end of August. The outside temperature was +36°C at that time. This rose to +42°C to +45°C during the daytime when the sun was actually out.
     
  17. NascentOxygen

    Staff: Mentor

    It's a good question, and one to which I have never had a satisfactory answer. Too many if's, but's and maybe's.

    If you consider an open weave, like fine netting, then perhaps light (IR, visible or UV) could penetrate deeper through reflection/s off white fibres? Whereas if the fibre were black, only those rays directed through the gaps between fibres would get in to heat beneath the robe.

    Relatives of mine lived in the Sahara for a couple of years, with a community that wore black dyed robes. The dye is actually a deep blue, and a tiny amount comes out of the fibre and stains their skin. The people are referred to by others as the blue people because of this blue hue to their skin. In this community, it was the men who wore a full head covering with blue gauze to see through. In the market the men would recognize each other by the children accompanying them; the women stayed in the home.
     
  18. BruceW

    BruceW 3,544
    Homework Helper

    Yeah, I'm from England, so we are always trying to keep warm. In fact, there is snow on the ground outside right now. I had a quick look on wikipedia (always my first point of call), and it said that when the surrounding temperature is greater than body temperature, then the only way the body can lose heat is by evaporation of fluid from the skin. (Which makes sense because net radiation and conduction is going to cause heat to flow into the body). So I would say that it would be best to wear clothing that minimises the flow of heat. This would explain why you should wear snug clothing. (But on the other hand, this might restrict evaporation). And I would guess it would be best to wear reflective clothing, so I'd say white clothing would be better. Maybe black clothing is worn because of tradition or because its the easiest colour to dye, or some reason not related to keeping people cool!
     
  19. That really is quite warm!! I think i've experienced. 35*C before....touching (or exceeding 50 though would be crazy).


    Not sure about an answer. How often peeps in how many deserts wear dark robes? It wouldn't be very effective to wear tight fitting clothes. Imagine wearing dark denim jeans when it's 39*C!!
     
  20. Sounds like no one here has been to the Mideast. When I lived in the UAE, which is incredibly hot in the summer, the traditionally clothed men wore white. The women wore black and were veiled, on the occasions when they left the house and went into public. Considering that men call the shots in that culture, I'd conclude that in a very hot sunny climate, white is better than black.
     
  21. cepheid

    cepheid 5,194
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    Way to NOT read the thread carefully. :tongue2:

    Yes, it is a patriarchal society, and yes, women in many ways are oppressed there. But I do not think that that oppression extends to deliberately trying to make women suffer discomfort for no good reason (which would be sadism). There's just nothing to justify that assertion. The motivation for the burka has to do with the extreme notion that exists in that society of what modesty is. Assuming that the difference in colouration is motivated by practical knowledge of heating and cooling, rather than just being simply cultural (which is a much more likely explanation) is just silly. I think that the Burka is just traditionally dark coloured, and the stereotypical "Arab dude" costume is just traditionally white. There is no explanation other than simply, "that's the way it has always been."

    Besides, we haven't yet established conclusively whether the black, loose flowing burka isn't *better* than the white, loose flowing Arab dude outfit. So using your own tenuous assumptions about another culture to come to some sort of conclusion about physics seems even more unsound.
     
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