Volcanic eruptions contribute to the dust level in the air. Humans contribute to the pollution level by pumping soot and harmful gases produced by vehicles and industries into the air. NASA's Mission to Planet Earth seeks to understand how all of Earth's systems affect each other, including how air pollution affects the ozone layer. Whether bird, balloon, or aircraft, things that fly make use of certain important characteristics of air to stay aloft. Most air molecules reside in the lower atmosphere.
Air expands when warmed and contracts when cold.
Air moves, which creates wind and weather. Air has volume, mass, and density. Air exerts pressure, which is the basis of flight. Information from an under construction publication from the Teaching From Space Program within NASA's Aerospace Education Services Program . Return to Off to a Flying Start homepage.