科学美国人60秒 SSS 降温层

You've probably seen pictures of Greek villages, where every house is painted bright white. The paint reflects the intense sunlight of the Mediterranean 1. And it works pretty well to keep the houses from heating up in the sun. But it doesn't actively 2 cool them.

你或许见过希腊村落的照片，那里的房子都被粉刷成亮白色。这种颜色可以反射来自地中海强烈的阳光，能避免房子在阳光下升高。但是，却不能降低房子的温度。

To understand why, consider what the white paint does. Here's how optical scientist Xiaobo Yin of the University of Colorado describes it: "It's a mirror for the sunlight, it's also a mirror for the radiation as well."

为了了解其中的原因，考虑白色油漆的作用。对此科罗多大学的光学科学家尹晓波讲到“其既能反射阳光，同时也能反射太阳辐射。”

And it might seem like reflecting all those incoming rays would be a good thing. But the benefit is limited. Because what it really means, Yin says, is that the houses, well, "they don't release much energy." Release more energy, again in the form of infrared 3 radiation, aka heat—and you effectively get free A/C.

似乎能反射所有的射线，是一件好事。但是这种效益是有限的。因为，尹小波表示，这意味着，“这些房子也不能散发太多热量。”以红外线的形式释放能量(或者热量)——这样你就能免费的享受“空调”待遇。

So Yin and his colleagues built a material that does exactly that: reflects visible light, but also emits infrared wavelengths 4. Which gives it the power to actually cool. It's two layers: a top layer of polymer, packed with glass beads 5 just eight microns across—so they can absorb and then emit infrared radiation. And a silver coating on the bottom.

所以尹和他的同事们构建了这样一种材料：可以反射可见光，同时也可以释放红外戏。这样就可以降低房子的温度。这种材料有两层：聚合物顶层，其间的玻璃微珠间距仅有8微米——这样就可以吸收和发射红外线辐射。底层是镀银层。

The coating reflects 96 percent of solar radiation—a slight improvement on white and silver paint. But the game-changing part: it also has a cooling power of about 100 watts 6 per square meter. Translation: enough to cool a frying-pan-sized amount of water to about 15 degrees Fahrenheit 7 cooler than ambient temps. Even while sitting in the sun. The finding is in the journal Science.

涂层能反射96%的太阳辐射——这种涂层对白色和银色漆料进行了略微的改善。但是其颠覆性的成分在于，每平方米有100瓦的冷却能力。也就是可以将煎锅量的水降至比周围环境温度低15华氏度。即使是坐在太阳底下。该研究结果发表在《科学》杂志上。

That cool water example has wide applications. "This water can be used to cool a house, cool a data center, or even cool a thermoelectric power plant." That's Yin's colleague at the University of Colorado, Ronggui Yang. And he says it's a cheap way to cool things down. Just don't put the material directly on your roof. "It also cools down during the wintertime. And you do not want that to happen." No. Definitely… not cool.

冷却的水有广泛的应用。“这些冷水可以用来降低房子的温度、降低数据中心的温度，甚至用来降低热电发电站的温度。”尹在科伦多大学的同事杨荣归说到。他还说道，这种降温的方式价格低廉。只是不能将这种材料直接放到房顶上。“在冬季，它也可以降温。你当然不希望在冬天发生。绝对不……因为已经够冷了!”