Relative humidity

Relative humidity is defined as the ratio of the actual amount of water vapor in the air to the maximum amount it can hold at a specific temperature [1]. The moisture-holding capacity of air is entirely dependent on its temperature; warmer air has a higher capacity to retain moisture than colder air [3]. According to the Clausius-Clapeyron relation, as temperature increases, the saturation vapor pressure (capacity) increases. Consequently, if the absolute amount of water vapor remains constant, an increase in temperature leads to a decrease in relative humidity because the air's capacity to hold moisture has expanded [3]. Conversely, cooling the air reduces its capacity, thereby increasing the relative humidity [2]. Therefore, relative humidity is inversely proportional to temperature, meaning it decreases as temperature increases.

Sources

1. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 24: Hydrological Cycle (Water Cycle) > Relative Humidity > p. 326
2. [3] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 10: Water in the Atmosphere > CHAPTER > p. 86
3. [2] https://www.sciencedirect.com/topics/engineering/water-vapor-saturation-pressure