CAPF AC 2022 Q63: Geography – Atmosphere & Climatology
- (a) Temperature is highest at ground level and decreases with increasing altitude.
- (b) Temperature is lowest at ground level and increases with increasing altitude.
- (c) Temperature remains stable with increasing altitude.
- (d) Temperature first increases with increasing altitude and gradually starts decreasing.
Answer: (a) Temperature is highest at ground level and decreases with increasing altitude.
Explanation
Normal lapse rate
How to think: the air is heated mainly from below, by the warm ground, not directly by the Sun.
So the air is warmest near the ground and gets colder as you go up.
This steady fall is the normal lapse rate.
| Term | Meaning |
|---|---|
| Normal lapse rate | Temperature falls with height, about 6.5 °C per kilometre (1 °C for every 165 m) |
| Temperature inversion | The reverse case: temperature rises with height for some distance |
Why hill stations are cool: Shimla or Ooty are colder than the plains because of the lapse rate.
Where it applies: in the troposphere, the lowest layer.
In the stratosphere the temperature rises again because ozone absorbs ultraviolet rays.
Answer: (a).
Why each option is right or wrong
- (a) CORRECT. Temperature is highest at ground level and decreases with altitude.
- (b) Incorrect. This describes a temperature inversion, not the normal lapse rate.
- (c) Incorrect. Temperature does not stay the same as you climb.
- (d) Incorrect. A rise followed by a fall is not the normal pattern in the troposphere.
Key point
Normal lapse rate: 6.5 °C per km (1 °C per 165 m) in the troposphere. Inversion: temperature rises with height; needs long winter nights, clear skies and calm air; traps smog and causes frost in valleys.
Remember
Normal lapse rate: 6.5 °C cooler per kilometre up.
Common mistakes
- Mixing up the normal lapse rate with a temperature inversion.
- Thinking it gets warmer higher up because you are closer to the Sun.
- Forgetting that the atmosphere is heated mainly by the ground.
Exam tip
Educated guess: think of climbing a mountain. It gets colder all the way up, and the peaks have snow.
Sources
- NCERT Class XI Geography — Fundamentals of Physical Geography, Chapter 9: Solar Radiation, Heat Balance and Temperature
- NCERT Class XI Geography — Fundamentals of Physical Geography, Chapter 8: Composition and Structure of Atmosphere