Question

The jet aircraft fly very easily and smoothly in the lower stratosphere. What could be the appropriate explanation?

1. There are no clouds or water vapour in the lower stratosphere

2. There are no vertical winds in the lower stratosphere.

Which of the statements given above is/are correct in this context? 

1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2

Answer 1

Correct Answer - Option 3 : Both 1 and 2

The correct answer is Both 1 and 2.

• The primary reason aeroplane flies in the stratosphere is because this is where the least amount of turbulence is found.
• This layer of the atmosphere allows for a much better fuel economy.
• This is because, in higher altitudes, such as those found in the stratosphere, there is less air resistance.
• The air resistance in the stratosphere is about half of the resistance found on the ground, which means the plane can hold airspeed at lower power settings.
• Clouds are found almost exclusively in the troposphere.
• The stratosphere is very dry, because the vertical transfer is limited by the high stability and because any transfer would have to occur through the tropopause, which is so cold that the saturation vapour pressure is negligibly small.
• Hence, statement 1 is correct.
• The increase in the temperature with height in the stratosphere makes this region a stable place where the air tends not to overturn vertically. Thus vertical winds are almost absent in Stratosphere. Hence, statement 2 is correct.

• Stratosphere
  • It is the second major strata of air in the atmosphere.
  • It extends above the tropopause to an altitude of about 30 miles (50 km) above the planet's surface.
  • The air temperature in the stratosphere remains relatively constant up to an altitude of 15 miles (25 km).
  • Then it increases gradually to up to stratopause. 
  • Because the air temperature in the stratosphere increases with altitude, it does not cause convection and has a stabilizing effect on atmospheric conditions in the region.