What does humidity mean in the weather forecast?

The air humidity in weather forecast refers to the degree of air humidity. General relative humidity. Relative humidity refers to the percentage of water vapor density actually contained in the air and saturated water vapor density at the same temperature. The optimum relative humidity for human body to feel comfortable indoors is 49% ~ 5 1%. If the relative humidity is too low or too high, people will feel uncomfortable.

Humidity, a physical quantity indicating the dryness of the atmosphere. At a certain temperature, the less water vapor in a certain volume of air, the drier the air; The more water vapor, the wetter the air. The degree of dryness and wetness of air is called "humidity". In this sense, it is often expressed by physical quantities such as absolute humidity, relative humidity, relative humidity, mixing ratio, saturation deficit and dew point. If the weight of steam in wet steam accounts for the percentage of the total weight (volume) of steam, it is called the humidity of steam. The comfortable humidity of human body is: the relative humidity is lower than 70%.