Why Black Clothes Heat Up Under the Sun

Perhaps many of you have noticed that the sun beats down on our backs way more when we wear a black T-shirt, and dark objects lying on a table on a sunny day also heat up more than lighter ones. This fact was relayed to all of us during childhood, however, we rarely ponder why this actually happens.

We at 5-Minute Crafts found out what the reasons behind this phenomenon are.

Light and color

From our school lessons on physics, we remember that light is not just a transparent white beam, but a complex of all colors of the visible spectrum. This phenomenon can be created independently by directing a beam of light through a glass prism, for example. Why does this happen? The thing is, the flow of light has a different speed depending on the medium where it is distributed (like air, water, or a vacuum). Getting into one of the faces of the prism, different colors that make up the beam of light move forward at different speeds, and, accordingly, they are seen differently when they leave the other face of the prism.

Reflection of light

When light is directed at an object, we see what color this object is. However, it’s important to remember what this is all about. The color of some items is actually the wavelength that was reflected from them and not absorbed. For example, in the light, a red T-shirt absorbs all the colors that make up white light except red, and we see it as red. The red wavelength is reflected from the shirt. A white shirt reflects all wavelengths of light without absorbing any of them, which is why we see it as snow-white and light.

Black items absorb all wavelengths without reflecting any of them.

Heat

It might seem that there is nothing special about the fact that black items absorb all visible wavelengths of light. But it is directly connected with the “rule” that one should ditch wearing black clothes until cooler weather sets in. This is because the light absorbed by a black T-shirt doesn’t just disappear to nowhere. It is converted into other types of energy — into heat, in particular. Accordingly, the darker the T-shirt, the more light it absorbs and the more heat it radiates. Since white clothes don’t absorb much light, they don’t emit heat either, which makes it very comfortable to wear in hot weather.