Air — Social Science STD 7 — Question

Troposphere: This is the most important layer of the atmosphere. Its average height is 13km. The air we breath exists here. Almost all the weather phenomena like rainfall, fog and hailstorm occur in this layer.
Stratosphere: Above the troposphere lies the stratosphere. It extends up to a height of 50km. This layer is almost free clouds and associated weather phenomenon, making condtios most idead for flying aeroplanes. One important feature of stratosphere is that contains a layer of ozone gas. We have just learnt how it protects us from the harmful effect of the sun rays.