Humidity refers to the amount of water vapor in the air, a general term encompassing several related measurements. Absolute humidity, on the other hand, is a specific measurement of this water vapor.
Understanding Humidity and Absolute Humidity
Humidity is a broad term describing the water vapor content of air. It doesn't specify how the water vapor is measured. There are several ways to express humidity, including absolute humidity, relative humidity, specific humidity, and dew point.
Absolute humidity, as defined by the provided reference, is the mass of water vapor present in a given mass of air. This is typically expressed in grams of water vapor per kilogram of air (g/kg). It directly measures the actual amount of water vapor present, regardless of the air's capacity to hold more.
Key Differences Summarized:
- Humidity: A general term; encompasses various ways to measure water vapor in the air.
- Absolute Humidity: A specific measurement of the mass of water vapor in a given mass of air. It provides a direct measure of the water vapor content.
Example:
Imagine two identical air parcels. One has a high absolute humidity (lots of water vapor) and the other a low absolute humidity (little water vapor). Both air parcels could have different relative humidities, depending on their temperature and the air's capacity to hold water vapor at that temperature.
The reference states: "Absolute humidity is the amount of water vapour present in a given mass of air at a particular time and temperature, while relative humidity is the ratio of the amount of water vapour present in the atmosphere to the maximum amount of water vapour the air can hold." This highlights the difference: absolute humidity focuses on the amount of water vapor, while relative humidity considers the amount relative to the capacity.
