Relative humidity primarily depends on which factor?

Relative humidity is a measure of the current amount of moisture in the air compared to the maximum amount of moisture the air can hold at a given temperature. As temperature increases, the air can hold more moisture, so the relative humidity decreases if the absolute moisture content remains the same. Conversely, if the temperature decreases, the air can hold less moisture, which can lead to an increase in relative humidity.

When considering factors that influence relative humidity, temperature is the primary one because it directly affects the air's capacity to hold moisture. While air flow, ventilation, and general weather conditions can influence the moisture level in the air, they do not alter the essential relationship between the moisture content and temperature. Therefore, focusing on temperature provides a clearer understanding of why relative humidity changes under different conditions.