The Layers of the Atmosphere
The atmosphere is divided into five layers. It is thickest near the surface and thins out with height until it eventually merges with space.
1) The troposphere is the first layer above the surface and contains half of the Earth's atmosphere. Weather occurs in this layer.
2) Many jet aircrafts fly in the stratosphere because it is very stable. Also, the ozone layer absorbs harmful rays from the Sun.
3) Meteors or rock fragments burn up in the mesosphere.
4) The thermosphere is a layer with auroras. It is also where the space shuttle orbits.
5) The atmosphere merges into space in the extremely thin exosphere. This is the upper limit of our atmosphere.
http://www.windows2universe.org/earth/Atmosphere/layers.html
