Far above the biosphere and the ozone layer we have the ionosphere, where, fuelled by the sun, atoms and molecules are constantly being split into electrons and ions, which give the ionosphere its properties and its name. Since the pressure is extremely low (the entire ionosphere weighs less than one tonne!), the electrons and ions are allowed to exist for quite some time before they recombine.
http://www.physics.irfu.se/SEE/ (patience needed for s-l-o-w loading url)
