Correct Option
Both statements 1 and 2 provide appropriate explanations for why jet aircrafts fly easily and smoothly in the lower stratosphere.
- Statement 1: The lower stratosphere is largely free of clouds and water vapour. Most weather phenomena, including cloud formation and precipitation, are confined to the troposphere below. This absence of moisture and cloud cover ensures clear visibility and stable atmospheric conditions, reducing the risk of encountering adverse weather.
- Statement 2: The stratosphere is characterized by stable, horizontally layered air masses with minimal vertical air movement or convection currents. Unlike the troposphere, which experiences significant vertical mixing and turbulence due to convection, the lower stratosphere offers a calm and smooth flying environment, free from the updrafts and downdrafts that can cause bumpy flights.
The combination of these factors-a dry, cloud-free environment and the absence of vertical winds-makes the lower stratosphere an ideal region for jet aircraft operation, allowing for efficient and comfortable flights.
Incorrect Options
- (a) 1 only: This option is incomplete. While the absence of clouds and water vapour is a correct reason, the lack of vertical winds (statement 2) is equally crucial for smooth flight operations.
- (b) 2 only: This option is also incomplete. While the absence of vertical winds is a correct reason, the dry and cloud-free nature of the lower stratosphere (statement 1) is also a significant factor contributing to stable flying conditions.
- (d) Neither 1 nor 2: Both statements 1 and 2 are factually correct and directly explain the smooth flying conditions in the lower stratosphere. Therefore, this option is incorrect.