Topic: Refrigeration and Air Conditioning
If a certain mass of moist air in an air tight vessel is heated to a higher temperature, then
- A. Specific humidity of the air increases
- B. Specific humidity of the air decreases
- C. Relative humidity of the air increases
- D. Relative humidity of the air decreases
Answer: D. Relative humidity of the air decreases
Explanation: Specific humidity is the actual mass of water vapor present per kg of dry air, which remains constant since it is a sealed airtight vessel. However, as the temperature increases, the saturation pressure of water vapor (the capacity of the air to hold moisture) increases. Relative humidity is the ratio of actual vapor pressure to saturation vapor pressure. Since the denominator (capacity) increases while the numerator remains constant, the relative humidity decreases.