What effect does increased humidity have on perceived temperature?

Increased humidity makes the air feel warmer due to the way our bodies regulate temperature. When humidity levels are high, the amount of moisture in the air prevents sweat from evaporating efficiently from our skin. Evaporation is a key cooling mechanism the body uses to maintain its temperature. As a result, with higher humidity, the body's ability to cool itself is compromised, leading to a sensation of greater warmth.

This perception is often referred to as the "heat index," which combines air temperature and relative humidity to reflect how hot it actually feels to humans. In practical terms, on humid days, even if the thermometer reads a certain temperature, people often feel significantly warmer due to the increased moisture content in the air.

Understanding this concept is vital in HVAC applications, as it influences how systems are designed to control both temperature and humidity effectively, ensuring comfort in indoor environments.