Relative humidity is defined as ____________.

Relative humidity quantifies how much water vapor is present in the air compared to the maximum amount that the air can hold at a specific temperature. It is expressed as a percentage, where 100% indicates that the air is fully saturated with moisture and can hold no more water vapor. Choosing the ratio of actual vapor content to the air's capacity captures this definition succinctly.

This concept is crucial in meteorology because it helps to explain weather phenomena and the comfort levels we experience in different atmospheric conditions. For example, high relative humidity can make temperatures feel warmer than they actually are, while low relative humidity can lead to more evaporative cooling effects, making it feel cooler. Understanding this ratio is fundamental for predicting weather patterns, cloud formation, and the likelihood of precipitation.