Cold air is dense, it builds and builds on the north pole, because that part of the earth doesn't get much sunlight. Space is a cold place. The air at the north pole becomes so dense that something has to give and like pouring water on a balloon the cold air falls toward the equator and look out here comes the cold air the leading edge is the cold front. Nothing stops a cold front a cold front can stop a hurricane in it's tracks. That hugh air mass the cold front can go all the way past florida. Michigan gets alot of cold fronts this time of year. Also as that cold front gets close to us it pushes on the atmosphere, and generally the wind comes from the southwest, so those windy days just might mean a cold front is on it's way.
h2o<-------hope's you learned something
