UPSC Prelims 2003 Q109: Geography – Atmosphere & Climatology
Assertion (A): The amount of moisture in the atmosphere is related to latitude.
Reason (R): The capacity to hold moisture in the form of water vapour is related to temperature.
- (a) Both A and R are individually true and R is the correct explanation of A
- (b) Both A and R are individually true but R is NOT the correct explanation of A
- (c) A is true but R is false
- (d) A is false but R is true
Answer: (a) Both A and R are individually true and R is the correct explanation of A
Explanation
Atmospheric moisture, latitude and temperature
| Part | Verdict |
|---|---|
| A. The amount of moisture in the atmosphere is related to latitude | True — moisture falls from the equator to the poles |
| R. The capacity to hold water vapour is related to temperature | True — warm air holds more, and temperature varies with latitude |
Both are true and R explains A: the moisture in the air varies with latitude because temperature, and so water-holding capacity, varies with latitude.
Answer: (a) Both A and R are true and R explains A.
Why each option is right or wrong
- (a) CORRECT. A is true and R gives the reason via temperature.
- (b) Incorrect. R does explain A, so this code is wrong.
- (c) Incorrect. R is true, so this code is wrong.
- (d) Incorrect. A is true, so this code is wrong.
Key point
Warm equatorial air holds up to about 4 percent water vapour; polar air only a fraction.
Remember
Moisture in the air decreases from the equator to the poles with temperature.
Common mistakes
- Thinking the amount of moisture is unrelated to latitude.
- Forgetting that capacity depends on temperature.
- Mixing absolute with relative humidity.
Exam tip
Latitude controls temperature, and temperature controls capacity.
Sources
- NCERT Class XI Geography — Fundamentals of Physical Geography — Water in the Atmosphere
- Savindra Singh — Climatology (Prayag Pustak Bhawan)