Air has to give up its heat to evaporate the water. The water heats up and becomes a vapor, and the air gives up its heat and gets colder. They exchange heat, basically.moda0306 wrote: Evaporative coolers confuse me.
I thought that when water evaporated, the temperature of the water cooled and the temp of the air rose. I also understand that humidity makes air "feel" warmer.
I don't fully comprehend the physics of it myself, but I understand that it has something to do with the "enthalpy of vaporization" and that water has a low enough point that hot air can vaporize it.
As for humidity, yes, it makes you feel hotter but the effect is only pronounced at high levels. Most of the time, the interior humidity in my house is under 20%, so low that my hygrometer can't take accurate measurements below that point. After the evaporative cooler has been running all day, the interior relative humidity is about 45%. It's very pleasant, Probably because the surrounding air is so cold. Extremely high humidity plus hot air is unbearable, but moderate humidity plus cold air is actually pretty nice. It's unusual, though, because most people are used to air conditioning, which removes moisture as it cools.