The Earth’s atmosphere extends above us thousands of kilometres and its physical properties and composition change dramatically at that distance. To simplify the study of the atmosphere it is split up into regions, according to these properties, and the names of the regions end in ‘sphere’. From lowest to highest these regions are:

  • The troposphere — from the ground to the height of the tops of thunderstorms, this region cools as you go up.
  • The stratosphere — warms as you get higher because ozone in the region absorbs energy from the sun’s ultraviolet (UV) rays.
  • The mesosphere — gets colder the higher you go.
  • The thermosphere — gets very hot, and is influenced by solar activity.

Atmospheric scientists at the Australian Antarctic Division are looking at the mesosphere and the ‘mesopause’ (the transition region between the mesosphere and the thermosphere) to see if things are changing due to natural or human made effects.