UPSC Prelims 2001 Q112: Geography – Atmosphere & Climatology
Which of the following weather conditions is indicated by a sudden fall in barometer
reading?
- (a) Stormy weather
- (b) Calm weather
- (c) Cold and dry weather
- (d) Hot and sunny weather
Answer: (a) Stormy weather
Explanation
Weather indicated by a sudden fall in the barometer reading
| Barometer reading | Weather |
|---|---|
| Sudden fall | Stormy weather — a low-pressure system (depression, cyclone) is approaching |
| Gradual fall | Rain likely |
| Steady rise | Fair, settled weather |
| High, steady | Calm, dry weather |
A sudden fall in pressure means a low-pressure system, such as a storm or cyclone, is coming. Rising or high pressure goes with calm, dry or sunny weather.
Answer: (a) Stormy weather.
Why each option is right or wrong
- (a) CORRECT. A sudden fall in pressure warns of a storm.
- (b) Incorrect. Calm weather goes with high, steady pressure.
- (c) Incorrect. Cold, dry weather goes with high pressure.
- (d) Incorrect. Hot sunny weather goes with steady or high pressure.
Key point
Barometer readings: about 1013 hPa at sea level; cyclones can have central pressures below 950 hPa.
Remember
Sudden barometer fall = storm coming.
Common mistakes
- Thinking low pressure means calm weather.
- Mixing a sudden fall with a slow fall.
- Not linking low pressure to rising, cloud-forming air.
Exam tip
Falling pressure = rising air = clouds and storms.
Sources
- NCERT Class XI — Fundamentals of Physical Geography, chapter 'Atmospheric Circulation and Weather Systems'
- NCERT Class VII — Science, chapter 'Winds, Storms and Cyclones'