Definitions for "Aeronomy"
A term denoting the physics and chemistry of the upper atmosphere. It is concerned with upper-atmospheric composition (i.e., nature of constituents, density, temperature, etc.) and chemical reactions.
aer*on*o*my \a(e)r-'an-o-me\n [fr. Gk aero-] a branch of science that deals with the atmosphere of the Earth and the other planets with reference to their chemical composition, physical properties, relative motion, and responses to radiation from space. Definition from NOAA.
The study of the atmosphere above about 50 km where dissociation and ionization are prevalent processes.