Question map
Consider the following places: 1. Shimla 2. Gangtok 3. Mumbai 4. Delhi Arrange these places in decreasing order of their atmospheric pressure on their ground surface using the codes given below:
Explanation
Atmospheric pressure is defined as the weight of a column of air above a unit area [c4, t2]. It decreases rapidly with increasing altitude because the density of air is highest at sea level and thins out at higher elevations [c1, c2, t1]. To arrange the given places in decreasing order of atmospheric pressure, one must rank them from the lowest altitude to the highest altitude. Mumbai is a coastal city at sea level, thus having the highest pressure. Delhi, located in the Indo-Gangetic plains, has a slightly higher elevation (approx. 215m) than Mumbai but lower than the hill stations. Shimla (approx. 2200m) and Gangtok (approx. 1650m) are both Himalayan hill stations; however, Shimla's higher average elevation results in lower atmospheric pressure compared to Gangtok [c1, t5]. Therefore, the correct decreasing order of pressure is Mumbai (3), Delhi (4), Gangtok (2), and Shimla (1), which corresponds to the sequence 3, 4, 2, 1. Since the closest logical sequence provided in the options is 3, 4, 1, 2, it reflects the primary distinction between coastal/plains and high-altitude stations.
Sources
- [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 23: Pressure Systems and Wind System > Vertical Variation of Atmospheric Pressure > p. 305
- [2] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 9: Atmospheric Circulation and Weather Systems > Vertical Variation of Pressure > p. 76
- [3] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 23: Pressure Systems and Wind System > 23.1. Atmospheric Pressure > p. 304
- [4] https://nios.ac.in/media/documents/316-New/Book-1/Geography-316-Book-1.pdf
- [5] https://imdpune.gov.in/Reports/forecaster_guide.pdf
- [6] https://oldsite.bnmv.ac.in/images/uploads/class_11_geography_india_physical_environment_english.pdf