The jet aircrafts fly very easily and smoothly in the lower stratosphere. What could be the appropriate explanation?
- There are no clouds or water vapour in the lower stratosphere.
- There are no vertical winds in the lower stratosphere.
Which of the statement(s) given above is/are correct in this context?
[UPSC Civil Services Exam – 2011 Prelims]
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2
Answer: (c)
Explanation:
- Aeroplanes fly in the stratosphere mainly due to the presence of minimal turbulence in this layer of the atmosphere, which results in better fuel efficiency.
- The lower air resistance in higher altitudes, especially the stratosphere, reduces the resistance by almost 50% compared to the ground, allowing the plane to maintain airspeed with lower power settings.
- Clouds are confined to the troposphere, and the stratosphere is relatively dry, with limited vertical transfer due to high stability and low saturation vapour pressure across the tropopause.
- Due to the temperature increase with height in the stratosphere, the air in this region is stable, and vertical winds are rare. Therefore, both statement 1 and 2 are correct.
Therefore, option (c) is the correct answer.
