Why does room temperature water give the sensation that it is cooler than room temperature air?



If I leave a glass of water on my nightstand overnight and drink it the next morning, the temperature feels notably cooler than that of the air surrounding me. What causes this sensation?

In: Biology

Water is denser and is a much better conductor than air. So basically, it doesn’t have to be that cold to take heat away from you quickly. The same reason metal tends to feel colder than you would think. 🙂

Water is a better conductor of heat than air, so while it may be room temperature, it will also move heat away from your hand/inside of your mouth.

This is most likely due to your receptors becoming accustomed to the temperature and sensation of surroundings. The water conducts heat differently to your body so it will probably be colder, but when you drink it, it’s a new sensation that stimulates receptors again.
When you dip one finger in “cold water” and one finger in “hot” water for x amount of time, then put them both in “warm” water, the finger that was in cold water will feel hot, and the finger that was in hot water will feel cold.
I hope this makes sense.

We don’t sense the absolute temperature of our surroundings. We sense the temperature of our own surface tissues and the rate at which it’s changing.

Our bodies are constantly generating heat and dumping it into the environment. Our skin exists at the boundary between the warm body and the cool environment, and its temperature is somewhere in between the two, dependent on the rate that heat is flowing. Water is approximately 1000 times denser than air, and has a much greater ability to absorb heat. Since water can carry away body heat much quicker than air, it causes the temperature of our skin to drop, which causes us to perceive that the water is cooler.

Water is much more thermally conductive than air. So heat flows out of your body quicker. It’s the same as stone floors vs carpeted floors. Or Metals versus plastic items.

When you touch something cold, what you are really feeling is the movement of heat from your body into the cold object. When something is more conductive, it will allow heat to move into it more quickly. Even though water is the same temperature as the air, water is more conducive, so the heat from you’r hand moves into the water more quickly, which makes it feel like it’s colder.

Worth noting that on top of the fact that what we feel isn’t temperature, which has already been mentioned, water is almost always actually cooler than the air.

This is because water constantly evaporates, and another way to think of evaporation is the fastest particles in the liquid jumping out of the liquid and becoming gas.

This overall cools the liquid because only the high energy molecules can leave, leaving water constantly being cooled until its fully evaporated.

Same reason why sweating works.

This causes the water to come to an equilibrium between the evaporative effect and the effect of normal heat transfer from the table/cup to the liquid. That equilibrium is lower than the actual average temperature in the room.

To add on to these comments, think of how your hand covered in water doesnt feel as cold as your hand covered in ethanol, which evaporates much faster. The ethanol is carrying heat away from your body at a faster rate which translates to a colder feeling.