Wearing dark vs light clothes in heat, which is truly better?

Great Debates
1

I have recently come to contemplate the age old idea that wearing white clothing in strong sunlight and heat is better at reflecting the suns rays, and ultimately keeping you cooler, than wearing black clothes in the same conditions. After an hour or two of searching for pertinent studies on PubMed, I was unable to find any strong sources to make a determination either way. So I resorted to Google searching, not to look for an answer from the public, but to maybe find what sources others were quoting. I quickly found a couple links where physicists made claim that actually dark clothes in the presence of at least 7mph winds were actually cooler to skin and body temperature than white. Counter intuitive claims are common on the internet, so I dug for the source of this conclusion. The study quoted was one done on birds. Seriously!? Birds. Any individual in a respectable science who feels that they can make a solid correlation between UV rays effect on bird feathers to human is simply the laughing stock of the science community. Please, does someone have any better research that shows the effects of sunlight heat on white vs dark clothes worn by humans!? A second article claimed that light clothes did in fact reflect sunlight, but also would reflect body heat back onto the body making the person hotter. I have to argue against this as well. Very simply, the heat generated from UV light is different than heat generated from cell metabolism and skin surface function. So sorry Esther Inglis-Arkell, your physics are poorly utilized in this situation. To claim that light clothes reflect body heat the exact same way they reflect UV converted heat is not only counter intuitive, but severely lacking in scientific support. Kate Kershner seems to feel that there have not been studies done on humans to date. Her article is the most reasonable I have found because it addresses this fallacy of the bird study relating to human UV interaction.

Just for reference, the two articles I mentioned above is here: The Physics that Explain Why You Should Wear Black This Summer

Walsberg, Glenn E. “Coat color and solar heat gain in animals.” BioScience. Feb. 1983. (Dec. 10, 2014) http://faculty.weber.edu/jcavitt/OrnithologyMaterials/Coatcolorinanimals.pdf

2

I look forward to the study in which physicists are randomized into two groups, one wearing dark clothing and one in light-colored clothes, both walking the streets of downtown Houston at high noon on a sunny July day.

Once we determine which group of physicists collapses first, we’ll have the answer. :slight_smile:

3

And color of the material may not reflect or block all sunlight allowing UV and IR to hit the body. A lot more characteristics of the material have to be factored in to make a determination about this.

4

AIUI, the reason black clothing works in African/Arabian deserts is because they are loose, flowing robes that generate the flow of air to cool the wearer down. Wearing black, tight-fitting clothing, on the other hand, is just asking to be baked in the Sun’s heat.
By and large white clothing would be better. At least anecdotally, when playing soccer in the hot sunshine, I always felt better in white than black.

5

All else being equal, emissivity will be dependent on color. But often there’s not a strong relationship between emissivity and color. According to this table, the emissivity of black paint is 0.95 and the emissivity of white paint is 0.84. Not a huge difference. As can be seen from the same table, emissivity is much more dependent on the type of material, not the color.

6

Just for completeness, the SD take.

7

Black would tend to stop the sun at the surface where it could radiate/convect away, while white would allow more light to pass through.

8

You’re thinking of translucence and opacity rather than color. It is completely possible to have white opaque materials and black translucent materials.

9

NM

10

A white t shirt on a sunny day is cooler than a black shirt, there is no question.

However, the Tuareg and some Arabian tribes wear dark colors, even if they are flowing robes it seems to me they would be hotter than white so I guess it’s still debatable. On the other hand perhaps they wear darker colors to stand out against white sand.