Why Does Black Absorb Heat?

When you think of the hot days of summer, what comes to mind? Long stretches of beach with waves crashing onto the warm sand? The sun shining brightly on a riverbank as you fish? Walking through tall pine trees on your way to a glacier lake?

If you had any of these images in mind, you might have also imagined yourself or your loved ones. Did you think about what you were wearing? If you pictured your favorite summer scene, there’s a good chance that the people in it were wearing white or other light and cool colors.

Why don’t we associate black or dark clothes with summer? Why are white and light colors the popular choices for summer? Although it may seem like it’s about fashion, the reason why white and lighter colors are more practical in the hot summer months actually has to do with science.

In fact, you’ve probably been told at some point in your life to avoid wearing black when it’s hot outside because black absorbs heat. Is there any truth to this statement? Or is it just an old wives’ tale?

If it was an older woman who told you this, guess what? She was partly right! Black clothing does absorb more light, which in turn converts to more heat. But why is that? It can all be explained by the science of light, heat, and energy.

To understand why black clothing absorbs heat, we need to first understand why black clothing appears black. The color of a shirt is determined by which wavelengths of light are reflected back from the object.

When light hits an object, that light (known as white light) contains all visible wavelengths. A red shirt appears red because it absorbs all wavelengths of light except for red, which it reflects back to our eyes.

A white shirt reflects all wavelengths of light back to our eyes, absorbing none of them. On the other hand, a black shirt absorbs all wavelengths of light, reflecting none of them back to our eyes.

As a black shirt absorbs all the light that hits it, it converts that light into other forms of energy, usually heat. It then releases that heat, some into the environment and some directly onto your skin. This is why people advise against wearing black or dark clothing on hot days, as it can make you feel hotter by absorbing light and emitting heat.

White shirts have the opposite effect. Since they absorb no light, they do not convert any of it into heat. This makes white or lighter-colored clothing cooler to wear in the summer.

Of course, while there is a scientific basis for the claim that black clothing absorbs light and converts it into heat, you may not really notice a significant difference between a black shirt and a white shirt on any given summer day. Many other factors, such as humidity and wind, contribute to how warm you feel on a particular day, regardless of the color of the shirt you are wearing!

Try It Out

Are you ready to experiment? Find a friend or family member to help you try out the following activities:

  • If you want to test what you learned today, go online and check out the science experiment “Do Different Colors Absorb Heat Better?”. You will need some materials and assistance from an adult friend or family member. Before starting, make some educated guesses about the expected results. Did the results turn out as you predicted? Why or why not?
  • It’s time to rearrange your closet! Take out all your shirts on hangers and organize them based on the amount of light they absorb, from the least to the most. On a hot day, try wearing shirts from different ends of the color spectrum. Do you notice any difference? Does one shirt keep you cooler?
  • Considering your knowledge about colors and heat absorption, how can you apply that knowledge in developing new products? Imagine yourself as a scientist and inventor, and think about the color choices for products, particularly clothing. If you were designing a shirt to keep people cool in the summer, how important would color be? What other factors would you consider equally or even more important?

Recommended Sources

  • http://mentalfloss.com/article/50506/why-do-black-shirts-get-hot-sun
  • http://www.knowswhy.com/why-does-black-absorb-heat/

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