Want to cool off? Jump in a pool. Better yet, get out of the pool!
Well here we go again as mid-90 degree temperatures are on their way back this week. With cooling rain showers few and far between, it looks like your best bet to cool off will be the local swimming pool again.
It’s easy to understand why jumping into 75° water makes us feel cool as we escape the 95° air, but why do we feel even cooler when getting out of the pool before wrapping up in a towel?
The cooling sensation you notice is referred to as evaporative cooling. Evaporation is the process of changing the state of water from a liquid to a gas (vapor). When you get out of the pool, the water on your skin begins to evaporate. More specifically, faster moving molecules in the water quickly escape into the air.
As those molecules escape the slower ones left behind have a lower overall energy level. The slower motion and lower energy level equate to a cooler temperature. A hot, dry day with low humidity aids evaporation. Thus, as the water evaporates, the temperature of your skin drops.
You'll probably feel even colder on a windy day, because wind helps the evaporation process even more. Our bodies take advantage of this by perspiring. The sweat that forms on our skin evaporates and acts like a natural thermostat on hot days.