What factor primarily influences the calculation of relative humidity?

Relative humidity is a measure of the moisture content in the air, expressed as a percentage of the maximum amount of water vapor that air can hold at a specific temperature. The primary factor in calculating relative humidity is the amount of water vapor present in the air, referred to as water vapor content.

The calculation involves comparing the current amount of moisture in the air to the maximum possible amount at a given temperature. If the air contains a significant amount of water vapor relative to its capacity, the relative humidity will be high. Conversely, if the air is holding less moisture, the relative humidity will be lower.

Other factors, such as temperature, do affect how much water vapor the air can hold and can consequently influence the relative humidity reading, but they do so in a way that is secondary to the actual amount of water vapor present. Wind speed and air pressure might impact local weather conditions and humidity indirectly, but they are not the main components in calculating relative humidity itself. Understanding that water vapor content is crucial allows one to assess how humid or arid the atmosphere feels, which is essential for various applications, including weather forecasting and climate studies.