Which term describes the ratio of water vapor in the air compared to the maximum amount it can hold at a certain temperature and pressure?

Relative humidity is defined as the ratio of the current amount of water vapor in the air to the maximum amount of water vapor that air can hold at a specific temperature and pressure, expressed as a percentage. It indicates how close the air is to being saturated with moisture. Understanding relative humidity is essential, especially in meteorology, as it influences weather patterns, cloud formation, and precipitation.

For example, when the relative humidity is 100%, the air is fully saturated, meaning it cannot hold any more moisture, leading to rain or dew formation. Conversely, lower percentages indicate drier air, which can impact comfort levels and the environment.

This term is distinct from others like absolute humidity, which measures the total mass of water vapor present in a given volume of air without regard to temperature, and dew point, which is the temperature at which air becomes saturated with moisture. Vapor pressure refers to the pressure exerted by water vapor in the air, which is a different parameter used in understanding humidity and saturation levels.