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This was another question from my son's workbook. It said:

Ever jumped into a pool on a warm day and still felt cold, even after measuring the 
temperature of the water with a thermometer and finding that it is the same temperature as
the air? Would this be conduction, convection or radiation then?

Interesting question. When he asked me, I immediately thought of convection, as that is 'conduction' of fluids, right? But I wasn't too sure, and I asked some friends. Both conduction and convection came as answers.

Which one is it? Why?

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  • $\begingroup$ It's a mix of conduction and convection. Heat conducts from your body to the interface of your skin and water, and the water molecules convect the energy away. $\endgroup$
    – Thermodynamix
    Commented Sep 9, 2019 at 22:52

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When first coming into contact with the water, it is conduction. The skin feels the water colder than air because water is a better conductor of heat than air. So the skin cools faster in water than in air.

For longer intervals convection will enhance the effect bringing cooler water next to the skin and removing the water already heated by the skin.

The difference will persist plotting water temperatures ( equal with air temperature) up to the temperature the skin raises the water when in contact with it. After that, the water is felt as warm.

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Convection, as the warmer less dense particles are at the surface of the pool while the colder denser ones at the bottom are gaining kinetic energy and are at the bottom this is a convection current.

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  • $\begingroup$ This is not entirely correct. The answer is both conduction and convection. Convection moves warmer water away from you towards cooler water and conduction transfers heat from your body to the cooler water. The displacement of water during the entrance into the pool is a form of forced convection through displacement... $\endgroup$
    – honeste_vivere
    Commented Mar 7, 2016 at 15:20

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