The relationship between temperature and relative humidity is primarily governed by the concept of saturation. Relative humidity (RH) is a measure of the amount of moisture present in the air compared to the maximum amount it can hold at a given temperature.
When air is heated, its capacity to hold moisture increases. This means that as temperature rises, the amount of moisture required to reach saturation also increases. If the actual amount of moisture in the air remains constant while the temperature increases, the relative humidity decreases because the air's capacity to hold moisture has increased.
To illustrate this, consider a hypothetical scenario where the air contains a certain amount of water vapor, and the temperature rises significantly without any additional moisture being added. As the temperature increases, the air can hold more moisture before becoming saturated. Consequently, the relative humidity decreases because the actual amount of moisture in the air represents a smaller proportion of its total capacity at the higher temperature.
It's important to note that this relationship assumes that the amount of moisture in the air remains constant as the temperature changes. In reality, humidity levels can vary due to factors such as evaporation, condensation, and the movement of air masses, which can lead to fluctuations in both temperature and relative humidity.