People who live in the Great Frozen North often notice in winter time that when cars run in the cold weather, white smoke comes out of the tail pipe, which goes away with the season. It also sometimes goes away if you run the car for a while.

Part One: Why does the white smoke go away?

Part Two: At a generating plant not far from here, on a cold day you can also see the same billowing white clouds of smoke. However, they can also be seen on some warm days, and some cold days, no white clouds. Why is this?

[ Car Talk Puzzler ]