Is there a medical term for that steam that comes out of person's mouth when they breathe in cold weather? What is that smoke thing called that comes out of your mouth as you speak when it's cold outside?

"The air you speak of is not a medical condition but a natural phenonemon. The 'condition' you refer to is 'vapor'. Seeing your breath when you're outside lets you know that it is indeed cold! The reason you can 'see' your breath is due to the water vapor in your breath. When you breathe in, water vapor is added to the air by your lungs, along with the carbon dioxide from your body. When your breath leaves your warm body and comes in contact with the cold air, it is immediately cooled. As it cools, the water vapor, which you cannot see, condenses into tiny water droplets, very much like the droplets in a cloud or fog. The particles are so small that they can't be identified by the eye either, but we see the light reflected off them much like smoke from a cigarette. So we really don't see our 'breath' at all, but we see the condensed water vapor droplets in our breath."


http://www.hollywoodindustry.com/2001/11_nov/tutorials/mayabreath.htm
http://www.howstuffworks.com/question195.htm

Carbon dioxide that's being expelled from your lungs as you exhale.It's warmer than the surrounding air,so appears as mist/smoke.