1. Chapter 3: The Atmosphere
3.1 The Air Around You

2. The Atmosphere A whole layer of air that surrounds Earth
Supports and protects life
Keeps Earth warm
Very thin

3. The Atmosphere Mostly made of gases.
Nitrogen (N) – 78%
Oxygen gas (O) – 21%
Argon, CO2, other gases – 1%
Some small liquid and solid particles
Dust, sea salt, water droplets

4. The Atmosphere
Nitrogen promotes plant growth and is in all living things.
Oxygen is needed for animals to breathe, energy for living things, and combustion.
CO2 is used to make food for plants.

5. Water Vapor Air contains water vapor – water in the form of a gas.
Plays an important role in the weather
Clouds are made of water vapor that condenses into droplets

6. Particles
Air contains solid and liquid particles, such as smoke, ash, dust, salt, and chemicals.

7. Atmosphere as a System
Events in one part of the atmosphere affect other parts of the atmosphere, as well as other parts of Earth’s system.
Wind and the ocean
Ocean currents and the climate
Storms

8. Chapter 3: The Atmosphere
3.2 Air Pressure

9. Density and Pressure Density: the amount of mass in a given volume
The more closely the particles are packed together, the more dense the object is.
Air pressure: the force of air pushing on an object; goes in all directions.

10. Measuring Air Pressure
Barometer: instrument used to measure air pressure.
Measured in units - bars
Mercury barometer: liquid mercury is moved due to pressure changes; when there is more pressure, it goes higher in the tube.

11. Measuring Air Pressure
Aneroid barometer: pressure causes the instrument to change shape slightly, leading to a needle moving inside of it.

12. Altitude
Altitude: elevation or distance above sea level

13. Altitude and Pressure
Sea-level air has the weight of the whole atmosphere pressing on it.
As you go higher into the atmosphere, there is less pressure pushing down.
As altitude increases, pressure decreases.

14. Altitude and Density
The particles in the air begin to spread further apart when you go higher in the atmosphere.
As altitude increases, density decreases.

15. Chapter 3: The Atmosphere
3.3 Layers of the Atmosphere

16. The Layers of the Atmosphere
The transfer of heat energy changes in the different layers of the atmosphere.
Troposphere
Stratosphere
Mesosphere
Thermosphere

17. Troposphere The layer nearest Earth’s surface
Contains about 80% of the mass in the atmosphere and almost all of the water vapor
Warmest at ground level and goes down about 6.5 degrees C every kilometer.

18. Stratosphere A clear, dry layer
Contains gas we call ozone. This absorbs a type of solar radiation that is harmful to life.
The radiation raises the temp of the air, and the temp rises the higher you go into the stratosphere.

19. Mesosphere The air is extremely thin here.
Contains less than 0.1% of the atmosphere’s mass.
Meteors burn in this layer.
The air here is heated from below, so the further you rise, the cooler it gets.

20. Thermosphere Starts about 90 km/56 mi above Earth’s surface
It gets less dense as altitude increases, but the temperature goes up.
The air high in this layer (closest to outer space) gets very hot from solar radiation

21. Chapter 3: The Atmosphere
3.4 Energy in the Atmosphere

22. Electromagnetic Waves
Energy from the sun travels in Electromagnetic Waves, or EM waves.
Most of it is in the form of Visible Light, Infrared Waves, and Ultraviolet waves.

23. Visible Light Visible light = ROYGBIV
Red has the longest wavelength; Violet has the shortest.

24. Nonvisible Radiation
Infrared – not visible by humans, but can be felt as heat.
Longer wavelengths than red light
Ultraviolet – also is invisible, but can cause skin damage and sunburns to humans.
Shorter wavelengths than violet light

25. Energy in the Atmosphere
Some of the energy is reflected or absorbed by the atmosphere; the rest reaches the surface.
Some UV radiation is absorbed in the ozone layer (stratosphere); most IR radiation comes closer to Earth’s surface and gets absorbed by water vapor and CO2.

26. Energy in the Atmosphere
About 50% of the sun’s energy reaches Earth’s surface as heat, and some of that is sent back into the atmosphere as IR radiation.
Gases called greenhouse gases keep heat in Earth’s atmosphere, close to the surface – called the greenhouse effect.
Human activity is changing the balance of this natural process, adding more greenhouse gases into the atmosphere.