In the height of summer, when the oven sun beams its burning energy into people’s skins, I wear black. Actually, I always wear black, I see it as the colour of discovery, of maturity, of reason, of clarity. (Of course, the slight detail that the 21st century’s worst war criminals saw themselves in black shows the silliness of ascribing symbolic meaning to colour.) But wearing black in the nasty sun, is that sensible?
Some colleagues and others have sometimes commented on my refusal to wear light colours on unpleasant blazing days. I find their comments a little odd, as though they haven’t seen the obvious. But, since people have been expressing these opinions at me for decades, perhaps what’s obvious to me isn’t so obvious to others. So here’s an explanation.
In the nasty summer sun, standing in the light, white clothes rather obviously reflect, whereas black clothes do not. Presuming the sun’s heat comes with the light, and I believe it does in the form of infrared light, etc., and presuming the clothes behave the same at those wavelengths as they do for visible light, then black clothes will quickly get hotter. White clothes are cooler in the cruel fire of sunlight. This, I believe, is the basis of the presumption that it is better to wear light in bright.
But it isn’t just the clothes that get hot, it’s the person wearing them too. There are a number of ways the body can get rid of heat, once of which is infrared radiation. Basically, you glow. It’s what infrared detectors pick up. It’s what people with infrared vision see. In the case of black versus white clothes, this is significant. The black clothes will absorb the radiation. The white clothes will reflect it back. Given that, for other types of cooling, black and white clothes are identical (colour does not affect airflow, the wet of sweat, etc.), then, for body heat, black clothes are cooler.
Now, obviously, the heat of the summer sun is much stronger than the heat coming off a hot person. But consider where you go in the horrible weather. Are you a foolhardy skin cancer fan who sticks to the burning light, or do you follow the expert advice and keep out of the sun as much as possible (for example, “… keep out the sun from 11am to 3pm, walk in the shade …”)? If, like me, you stick to the shadows, then, most of the time in these overheated days, the sun is not shining on either of us. That means, most of the time, there is no sunlight for the white clothes to reflect, or the black clothes to absorb. But, in the shade, my black clothes are still absorbing my body heat, whereas your white clothes are still reflecting your body heat back to you. Thus, if you are sensible, if you follow the advice, black clothes are cooler than white clothes.
So that’s my reasoning, but what does the science say? In the 1980s, some researchers asked why the most famous inhabitants of the desert, the Bedouin, wear black (grauniad). It turns out, for staying cool, colour is irrelevant for clothes (nature), and, interestingly, black is better if you sport feathers or fur. This was a surprise to me. So my presumption, above, that white is better in the hard sun, is wrong. Ok, so the research wasn’t exactly heavyweight (not that many experimental subjects), but it’s about the only empirical evidence I found, which is much better than guess–worthy self–opinionated exposition.
So, to summerise, if you work in an office in summer’s hot daze, or you keep to the shade, or you dance in the bright foul light, black is best.