How does evaporation cool us down?

Answer 1

The short answer is that the phase change that water undergoes when it evaporates is a process that consumes energy. Another way of looking at this is, in order for a given water molecule to evaporate, it has to be moving quickly enough to escape from the attractive force that other water molecules exert on it. Faster moving molecules have more kinetic energy, and are hotter. The hot molecules escape, leaving behind cooler ones. Then the cooler molecules also get warmed up by the warmth of the body, and fly away (or evaporate) taking that heat energy with them.

Answer 2

Evaporation cools us down by absorbing heat from our skin as water molecules on the surface of our body transition from liquid to gas. This process requires energy in the form of heat, which is drawn from our skin, thereby producing a cooling effect. This is why sweating helps regulate body temperature on hot days.