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Q29 (NDA-I/2009) Geography › World Physical Geography › Atmospheric moisture Answer Verified

The mass of water vapour per unit volume of air is known as

Result
Your answer: —  Â·  Correct: C
Explanation

Absolute humidity is defined as the actual mass of water vapour present in a given volume of air, typically expressed in grams per cubic metre (g/m³) [5]. Unlike other measures, it directly quantifies the water vapour density within a specific volume. In contrast, specific humidity refers to the mass of water vapour per unit mass of air (grams per kilogram) and remains constant regardless of pressure or temperature changes unless moisture is added or removed [1]. Relative humidity is a ratio, expressed as a percentage, comparing the actual moisture present to the air's total moisture-holding capacity at a specific temperature [5]. Therefore, the definition of mass per unit volume corresponds exclusively to absolute humidity [3].

Sources

  1. [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 24: Hydrological Cycle (Water Cycle) > Absolute Humidity > p. 326
  2. [3] Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 13: Weather > Notes > p. 120
  3. [5] https://www.weather.gov/lmk/humidity
  4. [1] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 10: Water in the Atmosphere > CHAPTER > p. 86
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