Answer:
Humidity is the amount of water vapor in the air. It is measured in terms of absolute humidity, relative humidity, and specific humidity.
- Absolute humidity is the mass of water vapor per unit volume of air. It is measured in grams per cubic meter (g/m3).
- Relative humidity is the ratio of the amount of water vapor in the air to the maximum amount of water vapor that the air can hold at a given temperature. It is expressed as a percentage.
- Specific humidity is the mass of water vapor per unit mass of dry air. It is measured in grams per kilogram (g/kg).
One method of measuring humidity is to use a psychrometer.
- A psychrometer is a two-bulb hygrometer that uses two thermometers, one dry and one wet. The wet bulb thermometer is covered with a wick that is saturated with water. As the water evaporates from the wick, it cools the thermometer. The difference in temperature between the dry and wet bulb thermometers is used to calculate the relative humidity.
Here is how a psychrometer works:
1. The two thermometers are placed in the air.
2. The wet bulb thermometer is covered with a wick that is saturated with water.
3. The water evaporates from the wick, cooling the thermometer.
4. The difference in temperature between the dry and wet bulb thermometers is measured.
5. The relative humidity is calculated using the following formula:
where:
- T_dry is the temperature of the dry bulb thermometer
- T_wet is the temperature of the wet bulb thermometer
- T_sat is the saturation temperature of the air
The psychrometer is a simple and accurate way to measure humidity. It is often used in weather stations, laboratories, and industrial settings.