Perspiration cools the body because

Perspiration cools the body primarily through the process of evaporative cooling. When sweat is produced on the skin, it must undergo a phase change from a liquid to a gaseous state to evaporate [2]. This phase change requires a significant amount of energy, known as the latent heat of vaporization [1]. The energy required for this evaporation is absorbed from the body's surface in the form of heat [3]. As the excess body heat is utilized to convert liquid sweat into vapor, the skin's temperature decreases, effectively cooling the body. While water does have a high specific heat, the cooling effect of sweating is specifically attributed to the loss of heat energy to the latent heat of vaporization during the evaporation process. This mechanism is a vital part of human thermoregulation during heat stress or physical activity.

Sources

1. [2] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 10: Water in the Atmosphere > EVAPORATION AND CONDENSATION > p. 86
2. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 22: Vertical Distribution of Temperature > Latent Heat > p. 294
3. [3] https://pmc.ncbi.nlm.nih.gov/articles/PMC9394784/