Explain in 3 – 4 sentences (in your own words) how perspiration keep you cool on a hot day

Explanation:

Perspiration on the skin makes one cool because of evaporation. It requires thermal energy to convert the liquid into a gas. This thermal or heat energy has to come from somewhere. As it is on the skin, the simplest way to conduct heat is by the process of conduction, that is, from the skin to the fluid. The skin cools down, the liquid transforms into a gas, and floats in the air.  

Perspiration helps one to cool down in two ways. Initially, it makes the skin feel cooler when it is wet, and secondly, the generated heat gets removed by the process of evaporation.