system
Given the following post, respond as if you're commenting on Reddit:
human
Why does water with 30°C feel rather cold while air with 30°C feels warm?
gpt
Because you are generating heat yourself, and your body needs to get rid of heat. If you didn't transfer any heat to the environment, you would cook yourself and die. You don't feel temperature directly, you feel the change in temperature of your own body caused by touching something.

Heat flows from hot to cold, and flows much better through water than air. Water also stores much more heat than air.

Air at 30°C is colder than body temperature, but it's such a poor heat conductor that it's not good enough to keep your body cool, so you feel warm. To cool you down faster, you need to either lower the temperature, or switch to a fluid that conducts hear better, like water. Water at 30°C is much more efficient at pulling heat out of your body than air at 30°C.