With the arrival of the heat, we look for a thousand ways to keep ourselves as cool as possible. We look for shade, air-conditioned interiors, we avoid going out during the central hours of the day and also, in many cases, we dress in the clothes that we think will best protect us from the sun.
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Since always, the idea of orSar light-colored fabrics when we are outdoors has been the best option to avoid being so hot. In most cases we avoid wearing black clothes because we believe that it makes us sweat more by absorbing the light. Is this true? What real impact does color have on heat when it comes to clothing?
How color influences heat
When the sun beats down on a hot summer day, it emits a combination of bright light and radiant heat. This sunlight is a mixture of wavelengths that include visible, infrared, and ultraviolet light. Light colored clothing reflects most of the visible wavelengths which in turn absorb less heat.
In contrast, darker or black clothing (followed by purple, blue, green, yellow, orange, and red) absorbs more wavelengths, more heat, and therefore makes the clothing warmer. But even if dark clothing absorbs more heat, it does not necessarily mean that the heat is transferred to the person wearing it. We must take into account other external conditions.
Black or white clothes in summer?
Black and white are at opposite ends of the color spectrum. White is a combination of all colors. This means that a white shirt will reflect most of the light and will not get very hot.
Arturo Quirantes, Professor of Physics at the University of Granada and author of the blog for popular science The Physics teacher, recognized a few years ago that white is better than black for less heat absorption.
This means that it reflects the sun’s rays instead of being scorched. But this is only half true, because heat doesn’t just come from the sun. Also from our sweaty body. Why do Bedouins in the desert regions of North Africa wear black clothes? They wouldn’t if there wasn’t a clear advantage.
When this body heat hits white clothing, it is reflected directly back to the body. The color black, on the other hand, absorbs all the heat from the sun, but also absorbs that of the body instead of reflecting it.
With a little wind, black clothing helps us stay cool because it favors what is called convection, that is, heat is transferred by the movement of air or fluid mass. Thanks to the wind and because the clothes are loose, the heat absorbed from the body is expelled.
The black clothing would act as a kind of fireplace: it heats the space between the fabric and the skin and forms an upward air current, which adds to the cooling of the body. But there has to be an air gap between the fabric and the skin.
This would explain why in the desert they wear black clothes. A study published a few years ago in Nature on the use of wide black robes by desert Bedouins, he suggested that the amount of heat gained by a Bedouin exposed to the hot desert is the same as that gained by wearing white clothing.
The difference between the two colors is that the heat absorbed by the black robe is lost before it reaches the skin. Convection cooling occurs inside clothing for several reasons: because the tunic is spacious, because the wind flows inside, and because a kind of chimney effect can occur.
According to this research, and at least in the case of Bedouins and their clothes, black is just as effective as any other color as long as other factors such as clothing thickness and slack.
The same would happen with the nomadic tents of the desert. Two physical effects converge in them: the shadow they produce and the ventilation. By better absorbing solar radiation, the black clothes in the store produce a better shade than a white one of the same thickness. And, to prevent the hot air from being inside, they open the stores completely.
Fabric matters too
As we have seen, one of the most important factors to refresh ourselves is to evaporate sweat from the surface of the skin. Therefore, any fabric that we use that allows sweat to evaporate more easily will make us feel cooler. In general, loose-fitting clothing that allows air flow is best.
We are talking about fabrics like cotton, bamboo or linen. Cotton is a fabric known above all for its breathability, although it wrinkles easily. Bamboo fabric is perfect for the summer months because it does not adhere to the skin, does not trap odors, does not wrinkle and has the ability to quickly evaporate moisture.
Linen is a very light, loose and fluid breathable fabric. It does a good job absorbing moisture and dries quickly. We can also talk about some special materials, such as technical sports fabrics, which are effective in wicking away perspiration.