Why is relative humidity considered a comfort factor in summer?

Relative humidity is a crucial comfort factor in summer because it directly influences the rate at which sweat evaporates from the skin. When humidity levels are high, the amount of moisture in the air increases, meaning the air is less capable of absorbing additional moisture, such as that from perspiration. Since evaporation is a key mechanism for cooling the body—sweat cools the skin as it evaporates—high relative humidity can lead to a feeling of discomfort, as the sweat remains on the skin rather than evaporating efficiently. Conversely, lower humidity allows sweat to evaporate more readily, enhancing the body's natural cooling process and creating a more comfortable environment. Hence, understanding and managing relative humidity is essential for maintaining thermal comfort during hot weather.