Which layer (name) is the 2nd least important and why? Answer and get to be the Brainliest! :)

Troposphere is considered as the most important layer of atmosphere. It is the lower most layer of the Atmosphere. Its average height is 13 km. The thickness varies from 8 km to 18 km, with maximum at equator and minimum poles. All the atmospheric phenomena such as rains, wind, clouds, etc. take place in this layer. Troposphere contains roughly 80% of the mass of Earth's atmosphere and it composed of composed of nitrogen (78%) and life giving gas oxygen (21%) with small concentrations of other trace gases. Hence, Troposphere is very important for the existence of life on earth as it causes the cloud formation, raining and maintaining the heat balance of the earth.