This abundance difference is a result of the way secondary cosmic rays are formed.

The smaller pieces are called "secondary" cosmic rays, and they in turn hit other air molecules resulting in more secondary cosmic rays.

Secondary cosmic rays, caused by a decay of primary cosmic rays as they impact an atmosphere, include neutrons, pions, positrons, and muons.

Atmospheric neutrinos are secondary cosmic rays produced by the decay of particles resulting from interactions of primary cosmic rays (mostly proton) with Earth atmosphere.

Secondary cosmic rays consist of the other nuclei which are not abundant nuclear synthesis end products, or products of the Big Bang, primarily lithium, beryllium and boron.

In this framework, we develop the theory of atmospheric electric field effects in the hard- and soft-muons of secondary cosmic rays and in the neutron-monitor counting rates as well.

The cosmic rays that arise in extrasolar astrophysical sources are primary cosmic rays; these primary cosmic rays can interact with Interstellar medium to create secondary cosmic rays.

Other sources include X-rays from medical radiography examinations and muons, mesons, positrons, neutrons and other particles that constitute the secondary cosmic rays that are produced after primary cosmic rays interact with Earth's atmosphere.

This is the first time, daily variations in secondary cosmic rays from an underground muon detector are shown to be associated with planetary-scale meteorological phenomena in the stratosphere such as the Sudden stratospheric warming as well as the change in seasons.