1. Chapter One: The Atmosphere
Weather

2. Section 1: Characteristics of the Atmosphere
Composition of the atmosphere:
made mostly of nitrogen and oxygen
21% oxygen, 78% nitrogen
Remaining 1% made up of: argon, carbon dioxide, water vapor, and other gases

3. Atmospheric Pressure and Temperature
Atmosphere is held around Earth by gravity
Air pressure is strongest at Earth’s surface because more air is above you
As altitude increases air pressure decreases
Air temperature changes as altitude increases
Some parts are warmer because they contain a high % o gases that absorb solar energy
Other parts contain less of these gases and are cooler

4. Layers of the Atmosphere
Thermosphere: the edge of the atmosphere
Mesosphere: the middle layer
Stratosphere: the home of the ozone layer
Troposphere: the layer in which we live
Look at figure 3 page 6

5. Troposphere:
Densest layer
Contains almost 90% of the atmosphere’s total mass
Almost all the Earth’s carbon dioxide, water vapor, clouds, air pollution, weather, and life forms are in the troposphere

6. Stratosphere:
Air is thin, contains little moisture
Lower stratosphere= extremely cold
Temp rises as the altitude increases
Stratosphere=in ozone layer
Ozone layer= protects life on Earth by absorbing harmful ultraviolet radiation

7. Mesosphere:
Middle layer above atmosphere
Coldest layer
Temperature decreases as altitude increases
Temp can reach -93 degrees celsius

8. Thermosphere:
Uppermost layer
Temp increases as altitude increases (particles moving very fast)

9. Ionosphere: Home of the Auroras
Electrically charged particles=therefor called the ionosphere
In polar regions these ions radiate energy as shimmering lights called auroras

10. Section Two: Atmospheric Heating
Energy in the atmosphere
Earth receives energy from the sun by radiation
Energy transferred by waves
Conduction: energy transfer by contact
1. thermal conduction
2. thermal energy is transferred from warm to cold areas
Convection: energy transfer by circulation
1. cycle of warm air rising and cool air sinking causes movement of air-convection current

11. II. Greenhouse Effect
70% of the radiation that enters the Earth’s atmosphere is absorbed by clouds and Earth’s surface-this is converted into thermal energy (energy that warms the planet)
-short wave visible light is absorbed and reradiated into the atmosphere as long-wave thermal energy
B. Atmosphere is like a blanket that traps enough energy to make Earth livable

12. Radiation Balance: for Earth to be livable-energy received from sun and amount of energy returned to space must be approximately equal-the balance of incoming energy and outgoing energy is called the radiation balance
Increasing levels of greenhouse gases could cause a global warming

13. Section 3 (p. 14) Global Winds and Local Winds
Wind= the movement of air caused by differences in air pressure
Air rises at the equator and sinks at the poles:
-the equator receives more direct solar energy
-the air at the equator is warmer/less dense
-warm air rises and creates a low pressure area
-the warm air flows towards the poles
-the poles are colder and more dense so the air sinks
-this creates an area of high pressure

14. Pressure belts are found every 30 degrees
Air travels in many large circular patterns called convection cells
Convection cells are separated by pressure belts
Pressure belts=bands of high pressure and low pressure found at every 30 degrees latitude

15. The Coriolis effect
Winds do not travel directly north or south because the Earth is rotating
The apparent curving of winds and ocean currents due to the Earth’s rotation is called the Coriolis effect

16. Global Winds
The combination of convection cells found at every 30 degrees latitude and the Coriolis effect produces patterns of air circulations called global winds
The major global wind systems are:
Polar easterlies
Westerlies
Trade winds

17. Jet Streams: atmospheric conveyer belts
Jet streams are narrow belts of strong winds that blow in the upper troposphere

18. Local Wind
Local winds move short distances and can blow from any direction
Shorelines or mountains can produce temperature differences that cause local winds
Mountain and valley breezes are other examples of local winds caused by an area’s geography