What classification is an air shower?

An air shower is a phenomenon that occurs when a high-energy cosmic ray enters the Earth's atmosphere and collides with the nuclei of air molecules, creating a cascade of secondary particles.

In terms of classification, an air shower could be categorized as a subfield of astroparticle physics, which is concerned with the study of high-energy particles (cosmic rays) from outside the Earth's atmosphere. Air showers are also studied in the field of cosmic ray physics, which investigates the properties and sources of cosmic rays.

Furthermore, air showers can be classified based on the type of particles they produce and their energy range. For example, electromagnetic showers are produced by high-energy photons, while hadronic showers are produced by protons, neutrons, and other hadrons. The energy range of the particles in the shower can also vary widely, from a few GeV to tens of EeV (exa-electronvolts).