whether you believe in ghosts or not, ypu have to admit that stories of ghosts exist all around the globe. The best explanation of why ghosts mostly appear at night is perhaps because most people are scared of the dark since they can't see anything and imagine things to be there that aren't.However, there is a science-based theory too. The earth'atmostpherevis bombarded by solar rediation from the sun more during the atmosphere lose their electrons and become ions that restrict some froms of electrical activity in the atmostphere