What is the air humidity?

Generally speaking, the humidity is 1% when it is impossible to contain more water vapor in the air at the current temperature.

absolute humidity is the pressure generated by water vapor in the air. There is an upper limit of absolute humidity at a certain temperature, which is called saturation pressure, and the saturation pressure increases with the increase of temperature. The saturated pressure of water vapor at 1℃ is 11kPa(1 standard atmospheric pressure).

relative humidity is the ratio of absolute humidity to saturated air pressure at current temperature.

Usually, the humidity in the weather forecast refers to the relative humidity.

The less water vapor is contained in a certain volume of air at a certain temperature, the drier the air is; The more water vapor, the wetter the air. In this sense, physical quantities such as absolute humidity, relative humidity, relative humidity, mixing ratio, saturation deficit and dew point are often used to express it.

If the percentage of liquid moisture in wet steam accounts for the total weight of steam, it is called steam humidity.

Extended information:

At a certain temperature, a certain volume of air can only hold a certain amount of water vapor. If the amount of water vapor reaches the limit that the air can contain water vapor, the air will be saturated and the relative humidity will be 1%. In the saturated state, water no longer evaporates.

In this weather in hot summer, the sweat secreted by the human body is difficult to evaporate, and it is unbearable to feel sultry. On the other hand, autumn sometimes meets the "autumn tiger" of high temperature, but because the humidity is obviously reduced, people are sweating all over but rarely feel "stuffy".

if we encounter low temperature and high humidity in winter, people will feel damp and cold. Too little humidity in the air will also make people feel uncomfortable. When southerners first arrive in the north, coastal people often feel dry lips and even nosebleeds when they go to the northwest. Of course, this is a question of human adaptability.

there are three basic forms of humidity, namely, water vapor pressure, relative humidity and dew point temperature.

water vapor pressure (once called absolute humidity) indicates the pressure of water vapor in the air, and the unit is in hectopascals (hPa), with one decimal place;

the relative humidity is expressed as a percentage of the ratio of the actual water vapor pressure in the air to the saturated water vapor pressure at the current air temperature, taking an integer;

dew point temperature refers to the temperature when the water vapor content in the air and the air pressure are constant and the cooling reaches saturation. The unit is expressed in degrees Celsius (℃), with one decimal place. When equipped with a hygrometer, it can also measure the continuous record of relative humidity and the minimum relative humidity.

Reference: Baidu Encyclopedia-Air Humidity