Question

why does a pool at 72 degrees F feel cold, but air at the same temperature feel warm?

Answer 1

The answer to this question comes down to the way of heat transfer, the thermal energy from the hotter object to the cooler object. The normal human body temperature is roughly . And the given temperature of the surrounding (either water in the pool or air ) is .
As long as the temperature of the surrounding is lower than the temperature of the body, the I will give off heat. The amount of heat my body gives off and how fast it happens ( the speed of the heat transfer ) - both of them are important for the sensation of the warmth or cold that we feel ( if we lose heat then we feel cold and if we gain heat then we feel warm ).
The amount of heat transfer between the body and the surrounding medium and the speed of heat transfer both depends on how good of conductor that medium is.
The reason water feel colder than air is because water is better conductor of the two. When I hop into the water pool, heat escapes my body much more easily and much faster than it would if I were standing beside the pool in air. Because water takes more heat from my body and quicker, so, it feels cooler.