I have probably known the stock answer to "How does sweating cool a person down" since elementary school. I'm looking for a far deeper answer to the question on this thread. I googled the question, and the first answer google provided is this answer from the website www.explorit.org: "Imagine each of those as a drop of sweat that will evaporate taking a bit of your body heat away. So sweat helps cool you down two ways. First, it makes your skin feel cooler when it's wet. And when it evaporates it removes some heat." I actually don't fully understand the first way that explorit mentions how sweating helps cool a person down, but I'm not much interested in it either. I'm interested in exporit's second way that sweating cools a person down. I'm going to restate what explorit said without the pronouns: "When sweat evaporates, the evaporation of sweat removes some heat." Before just two days ago, I thought that the evaporation of sweat removes heat only because the sweat is hotter than a person's body. And I thought when the hot sweat evaporates, the hot sweat is removed from the person's body, cooling the person down. Now I'm not so sure that the sweat is hotter than a person's body heat. I don't think it's as simple as I thought before. In my thread, "How does a metering device on an A/C lower the pressure" on the Mechanical Engineering subforum, PF member Russ Waters made a response to me that casts a lot of doubt on my initial conceptions of this issue. I'm a student attending a HVAC program at a trade school. My instructor and I were discussing how the metering device on an A/C lowers the pressure in the A/C. On my thread "How does a metering device on an A/C lower the pressure", I mentioned how my instructor gave me an explanation that sounds like it is saying that the sensible heat of a refrigerant is decreased because part of the refrigerant's sensible heat is converted to latent heat. I mentioned that I have never heard of this before my instructor mentioned it. Russ waters replied "Sure you have. Every morning when you get out of the shower and feel cold. Every time you sweat." I know that it takes a relatively large amount of heat to convert water from liquid to vapor without even increasing the temperature at all. I will call this amount of heat necessary to change the state of a liquid to vapor the "Change of State Heat". Russ waters is saying that sweating cools a person because a person's body heat is used to make the change of state heat to convert liquid sweat to vapor when it evaporates away. I see two potential causes of how sweating can cool a person down: #1 Sweat is hotter than a person's body heat. When a person's sweat evaporates, the evaporation cools a person down because it gets that hot sweat off a person's body #2 When sweat evaporates, the human body heat is used to "power" the change of state of sweat from liquid to vapor. The sensible heat of the human body is decreased because the sensible heat of the human body goes to form latent heat in the sweat vapor. Is Russ Waters correct that sweating cools a person because the sensible heat in a person's body powers the sweat's turning into vapor? Is part of the reason that sweat cools a person down because sweat is hotter than a person's body heat and when a person's sweat evaporates the evaporation removes that hot sweat?