Today’s Wonder of the Day was inspired by Zachary. Zachary Wonders, “Why does black attract heat” Thanks for WONDERing with us, Zachary!
When you think of the dog days of summer, what comes to mind? Long stretches of beach with ocean waves breaking upon the hot grains of sand? Bright rays of sunshine reflecting off a river bank as you fish? Hiking amongst tall pine trees on your way to a glacial lake?
If those or similar images came to mind, you might have also pictured yourself or friends and family members. Did you think about what you were wearing? If you pictured your favorite summer scene, there's a good chance the clothes people were wearing were white or a similar light, cool shade.
Why don't we associate black or dark clothing with summer? Why are white and other light colors the popular summer shades? Although it might seem like the answer has to do with fashion, it's actually science that makes white and lighter colors more practical in the hot summer months.
In fact, you've probably been told at some point in your life to avoid wearing black when it's hot out, because black absorbs heat. Is there any truth to that assertion? Or is it simple an old wives' tale?
If it was an old wife who told you that, guess what? She was somewhat right! Black clothing absorbs more light and that, in turn, gets converted to more heat. But why is that? It can all be explained by the science of light, heat, and energy.
To understand the heat absorption properties of black clothing, we must first understand why such clothing appears black in the first place. The color of a shirt is determined by which wavelengths of light get reflected back from that object.
When light hits an object, that light (known as white light) contains all visible wavelengths of light. A red shirt will thus appear red because it absorbs all of the wavelengths of light except for red, which it reflects back to our eyes.
A white shirt reflects all of the wavelengths of light back to our eyes, absorbing none of them. A black shirt, on the other hand, absorbs all of the wavelengths of light, reflecting none of them back to our eyes.
As a black shirt absorbs all of the light that hits it, it converts that light into other forms of energy, usually heat. It then emits that heat, some into the environment and some directly into your skin. This is why people advise against wearing black or dark clothing on hot days, since it can make you hotter as it absorbs light and emits heat.
Of course, while there's a scientific basis for the claim that black clothing absorbs light and converts it to heat, you might not really notice much of a difference between a white shirt and a black shirt on any given summer day. Many other factors, including humidity and wind, factor into how warm you feel on a particular day, no matter what color shirt you may be wearing!