Aeronomy is the science of the upper region of the atmosphere, where dissociation and ionization are important.

The term aeronomy was introduced by Sydney Chapman in a Letter to the Editor of Nature (journal) entitled Some Thoughts on Nomenclature in 1946.

Today the term also includes the science of the corresponding regions of the atmospheres of other planets. Aeronomy is a branch of atmospheric physics. Research in aeronomy requires access to balloons, satellites, and sounding rockets which provide valuable data about this region of the atmosphere. Atmospheric tides dominate the dynamics of the mesosphere and lower thermosphere. Therefore, understanding of atmospheric tides is essential to understanding the atmosphere as a whole. Other phenomena studied are upper-atmospheric lightning discharges, such as red sprites, sprite halos, blue jets, and elves.^{[citation needed]}

Atmospheric tides form an important mechanism for transporting energy input into the lower atmosphere from the upper atmosphere, while dominating the dynamics of the mesosphere and lower thermosphere. Therefore, understanding the atmospheric tides is essential in understanding the atmosphere as a whole. Modeling and observations of atmospheric tides are needed in order to monitor and predict changes in the Earth's atmosphere.