View Full Version : Hot days...black or white?
I have been pondering this....on the hot sunny days, whats better to wear. A black wicking shirt or a white wicking shirt? At first, I would think that white would be cooler because it reflects more energy but black could be cooler if it evaporates sweat faster because of the dark color (evaporative cooling). I am thinking about doing an experiment with some thermometers and damp wicking shirts in the sun. Can someone save me the effert and tell me which one will actually be cooler in the sun when sweating? David S.
I say the white shirt will be cooler. You want the sweat to evaporate to taking up your body heat, not the heat from the sun.
The white will feel cooler, at least when you're in direct sunlight. I doubt you would notice much difference under the forest canopy. I tend to go with grey since white shirts get really crudded up after a week.
The other consideration is that mosquitos apparently prefer dark colors. However, I've never found the difference to be significant enough that I don't need repellant.
Was going to say same thing Kerosene posted. Even in the open, you're going to have that beast on your back, blocking the sun.
Lighter colors allow you to see ticks better, though you generally get these on lower parts of your body. There seem to be many more than usual.
Navy blue doesn't show the sweat pattern as much, not that it really matters. I just noticed that when I would complain about the heat, people would tell me that I needed to sweat more, and my shirt, cool max mesh, would be half-soaked.
Sleepy the Arab
I'd have to say black, mostly because if it is really hot and you're really sweating, the salt will make neat-o tie die patterns. You can't get that with a white shirt....unless your salt is black, in which case would have bigger things to worry about.
But Sleepy, then you can get those neat-o-tie-die pit stains as well:D . Personally I go with a color in between, red.
Dark colors appear dark because they absorb light rather than reflect it. Colors appear to be red or green or blue because light in those wavelengths are reflected off them, but others are absorbed. Light colors appear light, because they reflect the majority of light that strikes them across all wavelengths. Black clothing absorbs all light wavelengths well.
So, when the sun is beating down, do you want a shirt that is absorbing the suns heating rays or a shirt that reflects them?
I would prefer lighter colors that reflect more of the suns rays.
Consider Bedouin and other desert people in the Middle East. Aside from Omar Sharif in "Lawrence of Arabia" most wear light color robes to protect them from the suns rays. I'll take that cue. There are very few people in the world with more experience in surviving hot, sunny environments than Bedouin nomads.
Sleepy the Arab
Not to sound like a smart-ass, but I feel I have to point out the obvious: the Bedouins live in deserts where it is 110 deg. The AT on the other hand, is protected from the sun by big leafy things we call trees.
Nonetheless, since 90% of all hikers have internal frame packs, it is kind of pointless to discuss the heat benefits of shirt color. Any heat "saved" by wearing a lighter shirt is negligable when compared to a very warm, very large and very close internal frame.
Sleepy, is that quote by Whitman from Howl
It was 100+ degrees during the day during much of my trip through in PA. It was well over 100 degrees Up Lehigh Pass and along the ridgeline there. This was 1995 and we had some record hot temps though.
The pack is a real stinker though in hot weather. Every little bit helps though.
On that nasty day, I wore my usual bandana and tucked my other bandana under it so thant it draped down the back of my neck. That made a HUGE difference in the "felt" heat. It made a little bit of shade on the back of my neck.
Bedouins wearing white....must have seen a different movie...most bedouins and nomadic desert people wear black. The following is from a DePaul Univesity web-site:
Question of the Week for January 20-27 Bedouins in the Sinai desert wear black robes. Experiments have shown that in bright desert sunlight such a black robe can be as much as 6o higher than a white robe. Yet a person wearing a black robe in desert conditions will actually be cooler than one wearing a white robe. What physics principles help explain this?
Answer (Jan 20-27). This question is an pplication of the first law of thermodynamics and is raised in Fundamentals of Physics by Halliday, Resnick and Walker. (We have seen excerpts from some of Walker's videos.) They give a brief answer based on an article in Nature (vol 283, Jan 24, 1980, pp 373-374). The authors of the article (zoologists from Tel Aviv and Harvard Universities) measured and/or calculated the rates of net heat gain by radiation, heat loss by convection and vaporation, heat storage, and metabolic heat production. Bedouins wear two layers of robes. Measurements showed that skin temperature was about the same (36o C) whether the outer robe was black or white. An outer black robe absorbs more heat than a white one, so it warms the air inside the robe more than the white one does. That warmer air rises and leaves through the porous fabric and cooler external air is drawn into the robe through its open bottom. The greater convection through the black robe enhances evaporation from the skin and so the black robe feels more comfortable. (Remember that evaporation is a cooling process.)
. . . so the layered black robes create sort of a bedouin air conditioning system...
Not that I'm going to bundle up in several layers in July...
however the dessert air is very dry while the air in the smoky mtns is very humid ..100% humidty at times and a lot of the time....so dessert wear wouldn't work under these conditions....
just like gore tex doesn't work under these conditions....
I wear a gray coolmax t-shirt that they gave me when I completed my LEAVE NO TRACE train the trainer program.... doesn't show dirt as bad and never gets dingy looky after repeated washing even in a bucket in cold water... fo course I have hauled this bucket of water for quater mile and use a biodegradable soap ...
is it sweat or humidity?????????
Sleepy the Arab
It is Walt Whitman, but it is not from 'Howl' but 'Song of Myself" from Leaves of Grass. Lovely poetry. Well worth taking on a hike of any length.
I was being funny, Howl was written in the sixties by Alan Ginsberg a beat poet . Howl was written in the same style. Well worth reading if you like Whitman.
I purchased a tan coloured coolmax shirt that lasted the whole AT froma local New Zealnd supplier. I am sure that in the good ol usa you will be able to find a nice shirt. At Bear Mtn NY it was 108 at noon last year when I was passing through so having a shirt that wicks away sweat is so important.