Does Wearing White Keep You Cool in the Summer?

You’ve probably been told before to wear white in the summer so you can keep cool. It’s something you probably just believed and never questioned–or tested. It’s not like you’re going to wear clothes of the exact same thickness and material in the exact same weather, with the only difference being your color of choice. Or maybe you have that scientific method in you and you actually did this, in which case you already know the answer to this question. But for those of us who just want to read the answer on our phones while we wait for the bus, does wearing white actually keep you cool in the summer?

Where does the idea come from?

There’s a reason “wear white when it’s hot” gets bandied around often. It’s because objects reflect the wavelength of light you see—so a red apple absorbs all colors that are not red, so red light bounces back into your eyeballs and you see red. “White light” has all colors from the visual spectrum, which means a perfectly white object absorbs no light. The idea is that light makes things hot and reflecting it will keep you cooler. 

Oops

So if white clothes reflected heat in a meaningful way, we would expect any population that lives in a very sunny place to wear white. Or at least avoid the color black—since it absorbs all the light. By “sunny,” you might be thinking of the desert.

Turns out the present inhabitants of the Sinai Peninsula, the Bedouin, wear black robes and herd primarily black goats. The Sinai Peninsula, by the way, is an arid desert. You might think this seems a bit counterintuitive, and so have scientists in 1980. Researchers Amiram Shkolnik, C. Richard Taylor, Virginia Finch, and Arieh Borut figured out pretty fast that black robes do direct more of the sun’s heat in than a white one would. This doesn’t line up with the Bedouin wearing all black in a desert though. That’s why we linked a research paper about it.

The researchers took someone and had them stand in the desert in four outfits; a black robe, a white robe, an army uniform, and shorts. It turns out the temperature increase in the sun was the same in both black and white robes—despite the black robes directing more heat inwards than their white counterparts. The key is that the robes are worn loose, and any heat retained by the clothing was lost before it ever made it to the wearer’s skin. What provides a relative cooling effect for the wearer is any kind of wind. The researchers concluded the cooling came from convection, which is the thing that makes hot air or water rise. 

More relevant to people who live outside deserts, Maria Hopman and her team of researchers at Radboud University have been following what people are wearing during the International Four Days Marches Nijmegen since 2007. The Four Day Marches are an annual event in the Netherlands and it’s exactly what it sounds like. Participants walk for four days, going 19, 25, or 31 miles per day (30, 40, or 50 kilometers respectively). Yeah they didn’t find a difference between white or black shirts either. They did find a day of walking increased human body temperature by about 1.8 degrees Fahrenheit (1 degree Celsius) though.


See if you know your white foods or something here. Maybe they’re cooler.

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