[FRIAM] We discussed this at the Friam Potluck

[thompnickson2 at gmail.com]

Nocturnal ice making in early India and Iran

In India before the invention of artificial refrigeration technology, ice
making by nocturnal cooling was common. The apparatus consisted of a shallow
ceramic tray with a thin layer of water, placed outdoors with a clear
exposure to the night sky. The bottom and sides were insulated with a thick
layer of hay. On a clear night the water would lose heat by radiation
upwards. Provided the air was calm and not too far above freezing, heat gain
from the surrounding air by  <https://en.wikipedia.org/wiki/Convection>
convection was low enough to allow the water to freeze.
<https://en.wikipedia.org/wiki/Radiative_cooling#cite_note-icemaking_radiati
ve-5> [5] A similar technique was used in Iran as well.
<https://en.wikipedia.org/wiki/Radiative_cooling#cite_note-6> [6] 

 

I confused the issue by insisting that the dish be a parabola. 

 

Nick 

Nicholas Thompson

Emeritus Professor of Ethology and Psychology

Clark University

ThompNickSon2 at gmail.com <mailto:ThompNickSon2 at gmail.com> 

https://wordpress.clarku.edu/nthompson/

 

 

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