Everyone knows what it’s like to be out on a cold and cloudless winter night when the skies are studded with stars. In the open, the cold is all too keenly felt. But in a forest, under the protective cover of the trees, it is less so. The reason for this difference is thermal radiation, which is emitted by the body and, depending on the nature of the surroundings, may be replaced by a smaller amount of radiation emanating from the environment. With a temperature of −270 degrees Celsius, the universe is far colder than our own immediate surroundings, and therefore emits hardly any thermal radiation. Research groups around the world have recently begun to explore novel methods for cooling buildings and clothing, even in broad daylight, by enhancing the rate of heat exchange with the universe—without the need for further energy consumption. However, potential applications of these methods for technological or experimental purposes—on a small scale—have rarely been investigated up to now.
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Source: Phys.org