Relative humidity is best defined as which of the following?

Relative humidity is best defined as the amount of moisture contained in the air compared to the maximum amount of moisture the air is capable of holding. This definition is crucial because it conveys the concept that relative humidity is a measure of how saturated the air is with water vapor at a given temperature.

As air temperature changes, its capacity to hold moisture also changes; warmer air can hold more moisture than cooler air. Relative humidity is expressed as a percentage, indicating how close the air is to being fully saturated. For example, a relative humidity of 50% means the air currently holds half of the moisture it can potentially hold at that temperature. This measurement is significant in various applications, including HVAC systems, meteorology, and understanding comfort levels in indoor environments.

The other choices do not accurately describe relative humidity. While temperature, air movement, and pressure are important factors in atmospheric science and engineering, they do not encapsulate the specific relationship between moisture content and air capacity that defines relative humidity.