This page contains information on the layer of the atmosphere called the Troposphere.  This layer is the closest to the Earth, the place where you live.  Most people will never leave this atmospheric layer.   The pie graph to the right displays the gas content of the atmosphere.

  The height of the troposphere varies all over the surface of the Earth.  The range extends from 6 to 8 kilometers at the poles to 17 kilometers at the equator.  Also, for every kilometer you travel away from the Earth, the temperature drops 6.5°C, but at an altitude of about 12km, the temperature stops dropping.  This area is called the tropopause.  It not only identifies the area in which temperature stops dropping, but is the boundary of the troposphere to the next layer of the atmosphere, the stratosphere.