Layers of the Atmosphere

Troposphere, stratosphere, thermosphere, and mesosphere are the four main layers of the atmosphere. The troposphere is the lowest layer and most of the clouds occur here. Containing most of the atmosphere’s mass, the troposphere extends twelve kilometers from the earth’s surface. A thin called the buffer zone divides the troposphere and the stratosphere. The layer above the troposphere is the stratosphere which contains the ozone layer. It extends from twelve kilometers to fifty kilometers and gets heat towards the top of the layer. Protecting the earth from meteoroids, the mesosphere is the coldest part of the atmosphere. Broken up into two layers, the thermosphere occupies the aurora borealis. The ionosphere and the exosphere are the two layers within the thermosphere. The ionosphere is a very thin layer which makes long-distance communication possible. Electrically charged gas molecules are what the ionosphere is made up of, whereas, the exosphere has many of the satellites.

http://csep10.phys.utk.edu/astr161/lect/earth/atmosphere.html