What is the difference between an ion and an atom

An atom can be an ion,  not all ions are atoms. The difference between an atom and an ion is net electrical charge.  ion is a collection of particles with a net of positive or negative charge.  A reliable atom has the same number of electrons as protons and has no net charge

No because the eaeht is on a 23.5 degree axis tilt and so when it is winter the northern hemisphere is pointing away from the sun and the soutubern hemisphere is pointing toward the sun