Question

the sphere is ideal for flight​

Answer 1

Explanation:

The troposphere is the lowest level of Earth's atmosphere. Above it, however, is the stratosphere, followed by the stratopause and then the mesosphere. Commercial jets can certainly fly above or below the troposphere, but this layer of the atmosphere offers ideal flying conditions for several reasons.

Answer 2

Commercial jet aircraft fly in the lower stratosphere to avoid the turbulence which is common in the troposphere below. The stratosphere is very dry; air there contains little water vapor.