Friday, 22 Feb 2019

Scientists revealed how the ancient Persian civilization can freeze water in the desert


IllustrationIllustration - Not many people know how humans in the past can freeze water in the desert. Physicists from the University of Pennsylvania reveal the way the ancient Persian civilizations of 2000 years ago made ice.

Without a cooling machine - just like it was done in the modern era, the ancient Persian people turned out to have their own technology to make ice.

Technology called 'night sky cooling' uses natural processes of sky power at night to start the process of freezing water. The deserts are dry and relatively cold and without clouds at night can easily change the water temperature.

The heat in the desert will be carried into space that has a temperature around minus 450 degrees Fahrenheit or minus 232 Celsius. Heat that comes out of the water reach the freezing point at a temperature of about 41 degrees Fahrenheit or 5 degrees Celsius.

With this technology, ancient Persian and Middle Eastern peoples can pour water into ponds of 30 to 60 centimeters in depth. After that, they will wait for the freezing process and return to the pool before sunrise.

That's when the process of 'harvesting' ice was then stored in a place called yakhcal or ice hole. This place is dome-shapedand can store ice in stable temperature for months.

"The water pool will send heat to the atmosphere, this concept is called thermal radiation, and the atmosphere and molecules in it absorb heat and send it back in the form of freezing temperature, but this atmosphere does not absorb all that heat" says University of Pennsylvania physicist Aaswath Raman.

"So the heat "runs away" into the sky, so the water in the pool sent a greater amount of heat to the sky so the pool can freeze."


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