If I fill a water bottle with room temperature water. And I put it in the shower. And I take a hot steamy shower. Why does the water in that bottle feel cold when I pour it?
In: Chemistry
Ever notice how water in a bottle feels cold after a hot shower? It’s because the bottle itself cools down faster than the water inside, making it feel colder when you touch it.
The feeling of cold isn’t about temperature itself, it’s about heat leaving your body.
We all know metal objects feel cold when you touch them: they aren’t any different temperature to say, a pillow, but they do conduct heat away from your body faster.
There’s two things going on. First, water has a very high heat capacity, meaning that it takes a lot of energy to warm it up. It might have seemed like a long time for you, but it was nowhere near long enough for the water in the bottle to equalize with the shower water.
Second is that your body’s heat receptors don’t really tell you whether something is hot or cold. They just tell you whether it’s hotter or colder than your body. So, you have a bottle of slightly-above-room-temperature water flowing over skin that had just got out of a hot steamy shower. It’s only natural that it will feel cool to you.
Water is really, really good at moving heat. It’s also really, really heavy and takes a lot of energy to warm it up.
In a hot steamy shower the room temperature water bottle (about 70 degrees) will absorb some of the heat from the hot shower water (around 100-130 degrees). The surface of your skin will warm up much faster as you bathe.
When you pour water out of the bottle over your hands, your warm skin will be cooled rapidly by the now 75-80 degree water, making it feel cold, even though it’s objectively quite warm.
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