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?