Cosmic rays enter the earth's atmosphere in large numbers every day and when one collides with an atom in the atmosphere, it can create a secondary cosmic ray in the form of an energetic neutron.
The atomic number of the atom is thereby increased by 1.
The positron and neutrino are emitted from the nucleus, while the neutron remains.
The atomic number of the atom is thereby reduced by 1.
Since Nitrogen gas makes up about 78 percent of the Earth's air, by volume, a considerable amount of Carbon-14 is produced.
Ever wondered how scientists know the age of old bones in an ancient site or how old a scrap of linen is?