Previous Year Question
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 statements given above is/are correct?
Correct Answer: C
Detailed Solution
Statement 1 is correct: Most weather phenomena—including clouds, rainfall, storms and atmospheric water vapour—are concentrated in the troposphere. The lower stratosphere above the tropopause is extremely dry and generally lacks weather-producing clouds.
Statement 2 is correct: Temperature increases with altitude in the stratosphere because ozone absorbs ultraviolet radiation. This arrangement, with warmer air above cooler air, makes the layer highly stable and strongly suppresses convection and vertical air movement.
Advantages for jet aircraft include:
Clouds and stormy weather are almost absent.
Convective vertical air currents are very limited.
Atmospheric turbulence is comparatively low.
Lower air density reduces aerodynamic drag and assists high-speed, fuel-efficient flight.
Scientific clarification: “No clouds or water vapour” and “no vertical winds” should not be interpreted as absolute zero. Water vapour and vertical motion are extremely limited in the stratosphere, although rare clouds and weak air movements can occur. The question refers to normal comparative conditions.