How is relative humidity calculated?

Relative humidity reflects the amount of moisture present in the air relative to the maximum amount of moisture the air can hold at a given temperature. The calculation for relative humidity is performed using the formula where actual vapor pressure is divided by saturation vapor pressure and then multiplied by 100 to express the value as a percentage.

Saturation vapor pressure represents the maximum moisture capacity of the air at a specific temperature, while actual vapor pressure signifies how much water vapor is currently in the air. Therefore, when you take the actual vapor pressure and divide it by saturation vapor pressure, you get a ratio of the current moisture content to the maximum capacity, which is then converted to a percentage for easier interpretation.

This approach is widely used in meteorology as it accurately conveys how close the air is to being saturated with moisture, a crucial factor in weather observation and forecasting.