Relative humidity is a measure of the amount of moisture in the air compared to the maximum amount of moisture the air can hold at a specific temperature. It is expressed as a percentage. For example, if the air can hold 10 grams of water vapor at a certain temperature and currently holds 5 grams, the relative humidity would be 50%. Relative humidity plays a crucial role in weather patterns and comfort levels. High relative humidity can make temperatures feel warmer, while low relative humidity can lead to dry skin and respiratory issues. Understanding relative humidity helps in predicting weather and managing indoor environments.