The correct option is 2 and 3 only.
Explanation
Humidity refers to the presence of water vapour in the atmosphere. It is quantified in different ways, including absolute humidity, specific humidity, and relative humidity, to analyze atmospheric moisture and weather patterns.
- Statement 1 is Incorrect: The weight of water vapour per unit weight of air is the definition of Specific Humidity. Relative Humidity (RH) is defined as the percentage of the actual amount of water vapour present in the air compared to the maximum amount of water vapour the air can hold at that given temperature.
- Statement 2 is Correct: Relative humidity is generally greater over the oceans than over the continents. Oceans provide a continuous and abundant source of moisture through evaporation, which keeps the air closer to its saturation point compared to landmasses where moisture availability varies.
- Statement 3 is Correct: The moisture-holding capacity of air is directly related to its temperature. Warmer air has a higher capacity to hold water vapour compared to colder air. Therefore, if the actual water vapour content remains constant, a change in air temperature will alter the capacity, thereby changing the Relative Humidity (e.g., as temperature rises, RH decreases).
Key Takeaway: Relative Humidity is a ratio expressed as a percentage that indicates the degree of saturation of the air. It is inversely proportional to air temperature when the specific humidity remains constant.