1. The Atmosphere

2. The atmosphere what is it?
A thin blanket of gases that surrounds the Earth
What does it do?
Controls the weather, water cycle, and the climate of the Earth.
Allows for life to exist on Earth

3. Atmospheric Composition

4. Atmospheric Composition
Aerosols – solids or tiny liquid droplets in the atmosphere other than gases.
Examples of aerosols:
dust
salt
pollen
volcanic ash
acids

5. Layers of the Atmosphere
The atmosphere is divided into the layers that you see in this diagram. These layers are based on temperature changes that occur with altitude. Each atmospheric layer has unique properties..

6. Layers of the Atmosphere
1. Troposphere - The troposphere is the atmospheric layer closest to Earth's surface. It extends upward to about 10 km. The troposphere contains about three fourths of the matter in Earth's entire atmosphere and nearly all of its clouds and weather. Temperatures in the troposphere are usually warmest near the surface and tend to cool as altitude increases.

7. Stratosphere STRATO = Layered
2. Stratosphere - Above the troposphere is the stratosphere. The stratosphere extends from about 10 km to about 50 km above Earth's surface. Most atmospheric ozone (O3) is contained in the stratosphere. This ozone absorbs much of the Sun's ultraviolet radiation. As a result, the stratosphere warms as you go upward through it, which is just the opposite of the troposphere. Without the ozone in this layer, too much radiation would reach Earth's surface, causing health problems for plants and animals.

8. Mesosphere MESO = Middle
3. Mesosphere - Above the stratosphere is the mesosphere This layer extends from approximately 50 km to 85 km above Earth's surface. This layer contains little ozone, so much less heat is absorbed. The temperature in this layer drops to the lowest temperature in the atmosphere.

9. Thermosphere THERM = Warm
4. Thermosphere - The thermosphere is above the mesosphere. The thermosphere extends from about 85 km to approximately 500 km above Earth's surface. Temperatures increase rapidly in this layer to more than 1,700 C. The thermosphere layer filters out harmful X rays and gamma rays from the Sun.
Because of intense interaction with the Sun's radiation, atoms in this region can become electrically charged particles called ions. For this reason a part of the thermosphere and mesosphere is called the ionosphere. This layer of ions is useful because it can reflect AM radio waves, making long-distance communication possible.

10. Exosphere
EXO = Outer
5. Exosphere - The outermost layer of the atmosphere is the exosphere. It extends outward to where space begins and contains few atoms. No clear boundary separates the exosphere from space.

11. Energy Balance

12. Water Vapor
Water content in the atmosphere is called the:
humidity
Composition varies as a function of temperature.
Warm air holds > 40 g H2O/Kg air
Cold air holds < 5 g H2O/Kg air
Addition/removal of water to the atmosphere requires/generates energy.
Importance to climate – water vapor transfers heat from warmer to colder regions
Latent heat – heat released or absorbed when matter changes state.

13. Latent Heat Cycle

14. Pressure Air Pressure – the weight of the overlying air
Measured in atm or bars (1 bar = atm)
1 atm is the weight of the atmosphere at sea level ~ 1,035 g/cm2
Mixture of gases in the atmosphere is not uniform
Air pressure decreases as one moves away from the Earth’s surface
As the pressure increases the density of the air increases

15. Air Density

16. Energy and the Atmosphere: Pressure, Water Vapor, & Weather
What drives energy within the Atmosphere?
Is the distribution of solar energy equal on the Earth’s surface?

17. Uneven Heating of Earth Surface
Solar energy is a function of both
Location
Time of year

18. June 1998 Mean Surface Temperature

19. What happens to hot air? Warm air rises
As air rises it enters a lower pressure area and expands
Expansion cools the air – the cold air can hold less water
Condensation occurs – clouds form (latent heat)
Which is more dense cold air or warm air?

20. Global Air Circulation

21. Where Will Precipitation and Evaporation Occur?

22. The Atmosphere in Motion
Air masses move from high pressure areas to low pressure areas

23. Coriolis Effect

24. Air Circulation Around a Pressure Low

25. Low and High Pressure Systems
Low Pressure
Air moves up
Weather cloudy
Usually associated with a cold front
High Pressure
Air descending
Little to no clouds – sunny

26. Wave-cyclones & Mid-Latitude Storms