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I've heard my parents saying that the water in earthen pots that are made in winters cools more than a pots that are made in summers. Is this true according to physics? I understand the process of water cooling in a pot , but what is the effect of environment temprature on the pots during manufacturing of pots?

I can think of factors like the density of water is maximum around 4°C ( that's the temperature during winters in Northern India), so when wet pots when placed for drying up in open (before putting then in furnace), as the water molecules evaporate,they expand Just before evaporation, that makes the pores in pots little bigger.

May be I'm wrong, there may be other factors like properties of a particular mud that is used for manufacturing. I want to know what is the scientific explanation for this phenomenon.

Thank You.

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  • $\begingroup$ For someone who is unfamiliar with how such pots are used, can you clarify how water cools in a pot? I ask because there's many mechanisms that I can think of that would lead to water cooling, and each mechanism may interact with the pot's structure differently. $\endgroup$
    – Cort Ammon
    Commented May 25 at 4:40
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    $\begingroup$ cools more What does that mean? Cools to a lower tempersture? Cools faster? $\endgroup$
    – Ghoster
    Commented May 25 at 4:50
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    $\begingroup$ I tried to do some initial research on this, didn't come up with much. But I would throw out a hypothesis that perhaps in that region of the world, the humidity during the winter is different than that of the summer. If so, the clay pots would dry very differently prior to firing, and that may lead to different sized pores. However, I can't offer this as an answer because I don't have any evidence to back it up. Perhaps someone can come up with some? $\endgroup$
    – Cort Ammon
    Commented May 25 at 4:58
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    $\begingroup$ Do you have samples of pot material that you can test and compare? Eg, pieces from old broken pots. You can measure the porosity of a ceramic sample by weighing it, boiling it in water, then weighing it again to determine the weight of water that it takes up. See digitalfire.com/glossary/clay+body+porosity $\endgroup$
    – PM 2Ring
    Commented May 25 at 9:43
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    $\begingroup$ @PM2Ring it's a nice approach. I have those two pots which I know, they are made in winter and summer . Can't break them for now. Although there are other pieces for this experiment but I don't know, when were they made. If 'll be able to do this in future, I'll update here. $\endgroup$
    – Gajjze
    Commented May 25 at 13:23

2 Answers 2

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water cooling in clay pots is caused by evaporation of water that seeps out of tiny pores in the pot, wetting its outside surface. The most likely answer is that the pots fired in winter are more porous than those fired in summer, and support a greater evaporation rate- and hence a greater evaporative cooling effect.

This would make for a very interesting series of experiments designed to test the basic hypothesis, and then to determine exactly where the seasonal effect on porosity after firing comes from!

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  • $\begingroup$ On what basis can we say that "pots fired in winters are more porous"? Enhanced cooling can also be a consequence of increased size of pores (may be). But not sure. Yes this need some experimental results for exact reason, that what is the physics behind it.. so for now I'm leaving this answer as unaccepted. Thank You.(& Sorry if it feels bad) $\endgroup$
    – Gajjze
    Commented May 27 at 2:56
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there may be other factors like properties of a particular mud that is used for manufacturing. I want to know what is the scientific explanation for this phenomenon

Earthenware cools water by allowing small amounts of it to move through pores then evaporate once it gets to the outside surface, removing heat, thereby cooling the water.

How effective this process is, depends on how porous it is, and that can come from various other factors. It may be that the ambient temperature (winter or summer) where it is made is one such factor. That is, the warmer environment in the summer leads to less pores, while those made in winter are more porous.

Of course, the number of pores, average thickness of each, number density (how many there are in an average volume) all have an affect on the permeability of water, and therefore how heat is transferred, and many other physical and chemical processes are occurring when making these pots. A more accurate answer to your question would be require more information.

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