Question

Aeroplanes fly in which of the following layers of atmosphere?
A.Mesosphere
B.Stratosphere
C.Troposphere
D.Exosphere

Answer 1

Hint: There are six layers in the Earth’s atmosphere and the sweet spot of flying an aeroplane is regarded to be between 35,000 to 42,000 feet.

Complete Step by Step Answer: Stratosphere is the layer of the atmosphere where planes usually fly. It usually extends up to 50 km above the ground. Most of the jet aircraft fly in the lower layer of the stratosphere, to avoid any turbulence, although thunderstorms do penetrate the stratosphere.
The sweet spot of flying an aeroplane is regarded to be between 35,000 to 42,000 feet because if the layer is too high, the oxygen level becomes too sparse to fuel the engines and if it is too low, there is greater air resistance. Passengers planes mostly fly in the lower stratosphere layer and also in the top level of tropopause because these are less turbulent layers and provide a smoother ride. The layer that exists between the troposphere and the stratosphere is termed as the tropopause.
Also, large passenger planes cannot fly at higher levels because the air is too thin above that and the oxygen level decreases.
Now let us examine the options
Option A – Mesosphere is the layer above the stratosphere which extends up to a height of about 85 km above the ground. This layer is not suitable for aeroplanes to fly because most meteors burn in this layer which is harmful. Also, unlike the stratosphere, the temperature is colder as you rise up through the mesosphere. The air present in this layer is too thin and continues dropping as one goes higher up.
Option B – The lower layer of the stratosphere is ideal for aeroplanes to fly because the temperature gets warmer as you rise up resulting in fewer clouds and water vapour which provides a smoother ride due to the absence of turbulence.
Option C – Troposphere is the lower layer of the atmosphere and lighter aircraft do fly in this layer but aeroplanes prefer to fly higher up this region to avoid any turbulences. This layer is vulnerable because most of the water vapour and cloud formation exists, resulting in thunderstorms.
Option D – Exosphere is considered to be the final frontier of Earth’s gaseous envelope and air present in this layer is extremely thin. This layer is more like a vacuum and is unfit for aeroplanes to fly in this layer.
Hence, from the above-mentioned points, the correct answer is option (B).

Note: There are exceptions, such as the commercial jet prefer flying in the troposphere region. The reason is that the air in this layer is thinner, making the commercial flight more fuel-efficient. So, the altitude selected for the flights or aeroplanes solely depends on the aircraft and engines they are employed with.