Changsha Panran Technology Co., Ltd.
Common humidity terms: helpful definitions
Source: | Author:J | Published time: 2025-04-27 | 10 Views | Share:

Humidity: the presence of water in a gas, most commonly the gas is air. Humidity amount can be measured and expressed using several different methods and measurement quantities.

Relative humidity (%rh): is the most common way to indicate how much water vapor is in a gas. It is expressed as the percent of water vapor saturation at the accompanying temperature. At any given temperature air can only hold a certain amount of vapor before saturation is reached and the vapor turns into condensation. So %rh is the percent of actual water vapor in ratio with the amount that would cause saturation.

Hygrometer: an instrument that indicates humidity. If the instrument measures humidity and air temperature, it is a thermo-hygrometer.

Psychrometer: an instrument that measures humidity using two thermometers. One thermometer is placed in a water-soaked sock so evaporation will cool the thermometer. A chart is used to convert the difference in temperature between the regular thermometer and the water-soaked thermometer as the temperature difference is rated to the evaporation rate which is related to humidity.

Dew point: the temperature at which a gas (usually air) is cooled to the point that 100% water vapor saturation is achieved so the vapor condenses. Dew point is often used in weather forecasting to describe humidity of air. Frost point is used when the condensation forms as ice. If you could attach a thermometer to your bathroom mirror, you could measure the precise temperature at which moist air from the shower condenses (fogs) onto the mirror. This temperature is the dew point in the bathroom. If you also measured the air temperature in the bathroom, you could combine that with dew point to calculate relative humidity.