Question 53 from UPSC CSE 2024 - Geograph y

Question

With reference to 'water vapour', which of the following statements is/are correct?
1. It is a gas, the amount of which decreases with altitude.
2. Its percentage is maximum at the poles.
Select the answer using the code given below:

IASCODEX · Accepted Answer

Correct Option: A. 1 only

Strategy: Focus on the climatic and geographic distribution of water vapour. Statement 1 aligns with atmospheric science: water vapour is highest near the surface and decreases with altitude. Statement 2 presents a clear red flag--water vapour is lowest at the poles, not highest. This directly leads to selecting statement 1 only.

Key Info: - Water vapour is a variable greenhouse gas crucial for weather and climate, predominantly found in the lower atmosphere (troposphere).
- **Geographic Distribution:**
  - Highest concentrations are found in warm, humid tropical regions, sometimes reaching up to 4% by volume.
  - Concentrations are significantly lower in deserts and polar areas, often less than 1%.
  - It diminishes from the equator towards the poles, with maximum concentrations in equatorial regions due to higher evaporation and warmth.
  - At the poles, extremely low temperatures prevent significant evaporation, resulting in minimal atmospheric water vapour.
- **Vertical Distribution:** Water vapour content rapidly decreases with increasing altitude because colder temperatures at higher elevations reduce the air's capacity to hold moisture.
- **Climatic Role:** It absorbs solar and terrestrial radiation, which moderates Earth's temperature (the greenhouse effect), and plays a critical role in cloud formation and atmospheric stability.

IASCODEX · Answer

Option B: 2 only

IASCODEX · Answer

Option C: Both 1 and 2

IASCODEX · Answer

Option D: Neither 1 nor 2

With reference to 'water vapour', which of the following statements is/are correct? It is a gas, the amount of which decreases with altitude. Its percentage is maximum at the poles. Select the answer using the code given below:

With reference to 'water vapour', which of the following statements is/are correct?

It is a gas, the amount of which decreases with altitude.

Its percentage is maximum at the poles.
Select the answer using the code given below: