Time for an experiment. On a sunny day, boil some water, pour it into a mug. Leave it.
Give it a few hours and it will be cold. If you touch it, it will feel cold. But logically it started off warmer than the air around it, and could not end up colder simply by being left to cool. The water is room temperature, according to current scientific theory.
But if you touch it, it will feel cold. Why is that, why would it feel colder than something that should be the same temperature?
And that's the point the more dishonest posters on this forum are going to stop reading, going to google the mainstream answer and then post that while yelling at me. Ignore them.
Because there is a supposed answer to this; heat capacity. The problem is that it's nonsense.
The idea is that it is harder to heat up water than it is air, because water being a liquid has many more molecules to heat up. Our bodies, being warmer, lose their heat to try and heat up the water/air and in doing so feel colder because they lose more heat to the water.
The problem is, this is nonsense.
There are a few ways to prove this. The first is a more interesting experiment, for warmer climes. When the natural temperature is around 100F, warmer than body temperature, perform the same experiment. You should have no reason to find the water cool if your body does not need to heat it up.
Otherwise, for the rest of us, there's an easy way to think about this. Water has more heat, that's what those molecules mean. There's a lot more tiny little balls acting to warm you up. Even when they're colder, they have far more energy than the air. That's part of it.
The second part is the most important though, and it's speed. if your body is genuinely losing some of its heat to warm up the water around it, it should not be basically instantaneous upon touching room temperature water. It takes time to lose heat, the difference between water and air should therefore take actual time to notice and make any kind of difference in what you feel.
the real explanation is trivial. Water is not intelligent, when it cools down it does not know how much energy needs to dissipate. If it sends too little, it has to keep cooling. Obviously then, eventually, it will need to send too much; sending the exact amount is so absurdly unlikely as to be impossible.
Now the air will try to warm it again, but the same holds. It sends too much, the water responds by doing the same. And that's just the surface level.
If you left it indefinitely, it would eventually even out, but that's assuming uniform temperature in the environment, which is unlikely.
It's simple, intuitive, the principle observed over and over, with huge implications. It's fundamental to certain FE models too.
And before you hit me with that 'but a thermometer says they're the same,' a thermometer cannot reasonably be expected to give an accurate reading from two separate mediums. A liquid imparts more pressure, thus gives a false reading of higher temperature. And, yes, the pressure can be exerted through the glass, matter isn't 100% rigid and unmoving.