Why is the pool cold on a warm day and warm during the evening ?.



 




It was a cloudy day when me, P & P decided to get inside the pool around 6 pm. Since it was our summer break and didn't get a chance to go for a swim for a while we decided to go even though it started to drizzle a bit. We were mentally prepared to feel the water cold compared to outside temperature. Instead, what we experienced was that the pool was warm and when we stopped swimming and came out of the water it was cold. It was very intriguing to note that our assumptions were wrong.

Even after I came back home and made a cup of tea the curiosity to understand why the pool water was warm compared to outside air was still lingering in my head. Suddenly, it dawned on me about the specific heat capacity of matters (water, air) I had studied during my school days and to confirm did a bit of reading and found the following.

Since the specific heat capacity of water is very high compared to air the water absorbs the heat during the day and feels warm when you enter the pool in the evening. It takes a long time to absorb the heat and retains the heat for long as well.  During the night when there is a huge temperature difference the warm water lets out the heat to the surrounding air and the air becomes warmer than the water in the morning.

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