<span>You may already know that when you breathe in, your body takes in oxygen from the air. When you breathe out, your lungs expel carbon dioxide back into the air. But the breath you breathe out contains more than just carbon dioxide.</span>
When you exhale (breathe out), your breath also containsmoisture. Because your mouth and lungs are moist, each breath you exhale contains a little bit of water in the form of water vapor(the gas form of water).
For water to stay a gas in the form of water vapor, it needs enough energy to keep its molecules moving. Inside your lungs where it's nice and warm, this isn't a problem.
