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Professors Claim Passive Cooling Breakthrough Via Plastic Film (sciencemag.org)
What if you could cool buildings without using electricity? charlesj68 brings word of "the development of a plastic film by two professors at the University of Colorado in Boulder that provides a passive cooling effect."
The film contains embedded glass beads that absorb and emit infrared in a wavelength that is not blocked by the atmosphere. Combining this with half-silvering to keep the sun from being the source of infrared absorption on the part of the beads, and you have a way of pumping heat at a claimed rate of 93 watts per square meter.
The film is cheap to produce -- about 50 cents per square meter -- and could create indoor temperatures of 68 degrees when it's 98.6 outside. "All the work is done by the huge temperature difference, about 290C, between the surface of the Earth and that of outer space," reports The Economist.
The film is cheap to produce -- about 50 cents per square meter -- and could create indoor temperatures of 68 degrees when it's 98.6 outside. "All the work is done by the huge temperature difference, about 290C, between the surface of the Earth and that of outer space," reports The Economist.
Mao's political method was to enter a village and kill every leader who didn't agree with him. Get a new set of leaders, kill every leader who didn't agree with him. Repeat until purified.
The words "nuance and subtlety" do not apply. His central committee was thugs and murderers like himself.
Just WTF are people being taught these days?
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Outer space is at ~3K/-270C: having that as your cold sink *day and night* is really quite significant.
Radiative cooling doesn't work that way: all that matters is your temperature. You don't radiate more into a cold area than a hot (a hot area sends more thermal radiation to warm you up, but that's orthogonal). It would be different if the atmosphere reflected IR, but that's not the case.
Socialism: a lie told by totalitarians and believed by fools.
in order to sink heat you must have something to heat, and vacuum just ain't that.
If you can get heat into radiative form (which this gadget can) and it doesn't get reflected back at you, effectively, it is sunk.
Second - I don't suppose there is some kind of magic involved in this discover, that magically allows IR radiation to bypass the several kilometers of atmosphere you have before outer space.
It's called an absorption spectrum. In this case, specifically it's called the Infrared Atmospheric Window.
Someone had to do it.
It doesn't work like that. Radiative heating/cooling works via exchange of IR. You're not just giving it up; everything you're radiating at is proportionally radiating back at you. So you cool the most when you're radiatively exchanging with something that's very cold. Aka, you want to be radiatively exchanging with the cosmic microwave background, not with low-altitude clouds. That's the whole point of radiating at low absorption frequencies in the atmosphere: so that you're exchanging with space, not with atmospheric air.
I'll never forget the last thing grandma said to me before she died: "What are you doing in here with that knife?!?"