3 ms·

> What we're talking about here is loosely analogous to air conditioning the entire Earth (with the heat being sent to space rather than the outside air). Sound

> What we're talking about here is loosely analogous to air conditioning the entire Earth (with the heat being sent to space rather than the outside air). Sounds like a hard engineering problem, but not impossible. It's possible to make radiative coolers that do exactly this, within limits. It's easy at night; harder in the daytime. Here's an example. https://www.futurity.org/radiative-cooling-system-2141732/ https://www.futurity.org/radiative-cooling-system-2141732/

betwixthewires 4y ago
That's not a very descriptive or explanatory article, I'd be very interested to learn more technically about this device if you happen to know or have anything.
- dreamcompiler 4y ago
  It's basic thermodynamics; if you leave a tray of water outside at night and you protect it from wind (convection) and insulate it from the ground (conduction) and there are no clouds, it will radiate heat away into the much cooler night sky. You may have ice in the morning, even if the ambient air temperature is above freezing. (This is also why cloudy nights are warmer than clear nights in winter--clouds prevent some of the ground's heat from radiating away.) The technique has been used for centuries to make ice in the desert, but it only works at night and it's inefficient. https://www.fieldstudyoftheworld.com/persian-ice-house-how-make-ice-desert/ https://www.fieldstudyoftheworld.com/persian-ice-house-how-m... With modern technology it's more efficient and it appears it can even be made to work in the daytime: https://energyindemand.com/2020/10/17/generations-after-people-learned-to-make-ice-in-the-desert-the-same-technique-under-development-to-provide-us-with-radiative-cooling/ https://energyindemand.com/2020/10/17/generations-after-peop... https://onlinelibrary.wiley.com/doi/10.1002/adpr.202000106 https://onlinelibrary.wiley.com/doi/10.1002/adpr.202000106

betwixthewires 4y ago

That's not a very descriptive or explanatory article, I'd be very interested to learn more technically about this device if you happen to know or have anything.

dreamcompiler 4y ago
It's basic thermodynamics; if you leave a tray of water outside at night and you protect it from wind (convection) and insulate it from the ground (conduction) and there are no clouds, it will radiate heat away into the much cooler night sky. You may have ice in the morning, even if the ambient air temperature is above freezing. (This is also why cloudy nights are warmer than clear nights in winter--clouds prevent some of the ground's heat from radiating away.) The technique has been used for centuries to make ice in the desert, but it only works at night and it's inefficient. https://www.fieldstudyoftheworld.com/persian-ice-house-how-make-ice-desert/ https://www.fieldstudyoftheworld.com/persian-ice-house-how-m... With modern technology it's more efficient and it appears it can even be made to work in the daytime: https://energyindemand.com/2020/10/17/generations-after-people-learned-to-make-ice-in-the-desert-the-same-technique-under-development-to-provide-us-with-radiative-cooling/ https://energyindemand.com/2020/10/17/generations-after-peop... https://onlinelibrary.wiley.com/doi/10.1002/adpr.202000106 https://onlinelibrary.wiley.com/doi/10.1002/adpr.202000106