Atmosphere and Air Pressure Notes Define atmosphere • Atmosphere –The whole layer of air that surrounds Earth –A mixture of gasses –Keeps Earth warm –Protects life Why is the atmosphere important? • • • • • Protects life Keeps the Earth Warm Allows talking/sound Provides weather Allows flight How does the atmosphere protect life? • Absorbing harmful radiation • Maintaining Earth’s temperature • Providing elements essential for life What materials make up the atmosphere? Gas Percent Nitrogen (N2) 78.08 Oxygen (O2) 20.94 Argon (Ar) 0.98 Carbon Dioxide (CO2) 0.04 Other Elements 0.01 Water Vapor (H2O) 0-1 Gases of Earth's Atmosphere What can change the atmosphere? • Natural Changes –The exact amounts of some gases in the air (atmosphere) change depending on: • Location • Time of day • Season What else can change the atmosphere? • Sudden Changes –Dramatic events may cause a change in the atmosphere –It may take a long time for the atmosphere to restore balance –Examples • Volcanic Eruptions • Forest Fires • Dust Storms Define Altitude Altitude • The distance above sea level Define density Density • The amount of mass in a given volume – The density of the atmosphere decreases with altitude – Most of the mass of the atmosphere is close to Earth’s surface What is air pressure? • Air Pressure – The force of air molecules pushing on an area. • Air pushes in ALL directions • Greater the force the higher the air pressure How does air pressure relate to density? • Air pressure and density are related – As density increases, air pressure increases – As density decreases, air pressure decreases LOW AIR PRESSURE HIGH AIR PRESSURE How does air pressure relate to altitude? • Air pressure decreases as you move higher in the atmosphere. – High Altitude = Low Air Pressure – Low Altitude = High Air Pressure Why dont you feel air pressure acting on you? • It is balanced. – The pressure pushing down on you is balanced by the pressure of air pushing up from below. How do we measuring air pressure? • Barometer – Any instrument that measures air pressure How did air pressure keep the card on the cup? How did air pressure get the balloon in the glass bottle? How did air pressure crush the can? How did air pressure keep the ping pong ball in the funnel? How did air pressure keep the ping pong ball floating?