What is the difference between specific humidity and relative humidity?

Specific humidity and relative humidity are important concepts in understanding atmospheric moisture.

Specific humidity refers to the actual mass of water vapor present in a unit mass of air, typically expressed in grams of water vapor per kilogram of air. This measure is a definitive quantity that directly reflects the amount of moisture in the air regardless of temperature or pressure.

Relative humidity, on the other hand, is a measure of how much water vapor is actually in the air compared to the maximum amount of water vapor that the air can hold at a given temperature, expressed as a percentage. This means that relative humidity is temperature-dependent because warmer air can hold more moisture than cooler air.

The statement detailing specific humidity as a measure of the mass of vapor and relative humidity as a percentage encapsulates this distinction effectively. Specific humidity is a fixed figure based on the actual content of moisture, while relative humidity fluctuates depending on the temperature and the air's capacity to hold moisture at that temperature.

Understanding the differences between these two measurements is crucial for applications in meteorology, climatology, and other fields where atmospheric moisture plays a significant role.