Physics explains why dark clothes are better than white in summer

As we gear up for summer, you always hear the importance of dressing accordingly. Through most of your life, you may have heard the importance of wearing lighter-colored shirts when outdoors; physics says otherwise.

While lighter-colored shirts that are loose fitting keep you cool during the dead of summer, if the conditions are just right, darker colors are actually better for you.

To begin to understand this, you must first understand what color is.

Color is defined as the property possessed by an object of producing different sensations on the eye as a result of the way the object reflects or emits light. The key here is the way clothing reflects or emits light because light energy can be converted into heat energy. In other words, the more light energy you absorb the more heat you’ll give off.

The blacker an object is, the more wavelengths of light that are absorbed by the object; true black absorbs all wavelengths. The opposite of this is the whiter an object is, the more wavelengths of light that are being reflected. So true white reflects all wavelengths.

So what does this have to do with the clothes you wear during the summer? All too often you hear the importance of wearing loose-fitting clothing that is lightly colored when going outside. That’s partially true.

On any given summer day, a white T-shirt that is loose-fitting will keep you cool, but if the conditions are just right, a darker color will actually keep you cooler. To understand this you must understand physics.

We’ve already discussed what color is and how light energy can be converted into heat energy, but now comes the actual physics of what shirts are best.

Imagine, if you will, walking outside in the heat with a white shirt on that is loose-fitting. What’s going on? The sunlight hitting the shirt is being reflected back out into the environment keeping you cooler, but there’s also something else going on.

The heat our body produces is also being reflected back onto us, therefore keeping us warmer. The reason this occurs is because lighter-colored objects absorb less photons. So while white T-shirts aren’t terrible ideas there are other alternatives.

If the conditions are just right, with winds over 7 mph, darker loose-fitting clothes are actually better for you.

The reason is actually very simple.

Remember how darker colors absorb more light, and therefore create more heat energy?

Well not only is the shirt absorbing heat from the sun, but it’s absorbing heat from our body as well.

This is where the winds come into play. If the winds are strong enough (7 mph or over), then it will take that heat and cool you through convection. You’ll have the heat leaving your clothes through the winds, which will in turn heat the atmosphere and keep you cooler than white clothes.

Another reason black is safer for you in the summer months, is because of its high ultraviolet protection factor. The darker a color, the more protection from the sun you’ll have, whereas the lighter the color, the less protection you’ll have from the sun. This could mean the difference between skin cancer and staying safe.

So this summer when you head outdoors, if the conditions are just right you may find yourself wearing darker clothes instead of lighter-colored clothes because of physics. Of course, heat is subjective and depends on the person and their body type.