1. Earths Atmosphere

2. Chapter 1: Earth’s Changing Atmosphere
1.1 Earth’s Atmosphere Supports Life
Air – mixture of gases
Atmosphere – layer of air that surrounds the Earth
1. Supports life and protects it
2. Keeps Earth warm
3. Transports energy

3. Characteristics of the Atmosphere
Altitude – distance above sea level
The thickness or thinness of air is measured by its density.
Density – the amount of mass in a given volume of a substance
*Atmosphere’s density decreases as you travel upward.

4. Gases in the atmosphere:
Nitrogen (N2) – 78%
Oxygen (O2) – 21%
Carbon Dioxide (CO2), argon, other gases – 1%
Nitrogen – promotes plant growth
Oxygen – animals and plants perform life processes
Carbon dioxide – plants use to make food

5. Cycles – processes that are repeated over and over again
1. Carbon Cycle :
a. Oxygen inhaled by animals, exhales Carbon Dioxide (CO2)
b. CO2 taken in by plants, releases Oxygen (O2)
2. Nitrogen Cycle :
a. tiny organisms (living things) remove N2 from air, changes it into other chemicals and returns it to the soil.
b. plants/animals use solids/liquids that contain N2, then return to soil when they die & decay.
c. soil slowly releases N2 back in the air
3. Water Cycle:
a. Liquid water from oceans & lakes changes into
gas (evaporates) and enters atmosphere
b. Plants release water vapor from leaves
c. Liquid water falls back to atmosphere as
precipitation – rain, snow, sleet, or hail.

6. Sudden Changes:
**Volcanic eruptions, forest fires, dust storms can cause changes in the atmosphere
Volcanic Eruptions – shoots gases and ash into the atmosphere.
Forest Fires – when forests burn, carbon that makes up the trees enters the atmosphere as carbon dioxide.
Dust Storms – Adds huge amounts of particles to the air.

7. Section 1.2: The Sun Supplies the Atmosphere’s Energy
Two main things happen to sunlight when it hits the Earth:
1. Sunlight is reflected – you see most objects by reflected sunlight
2. Sunlight is absorbed – sand absorbs sunlight & becomes warm

8. The Atmosphere Moves Energy
Processes that move Energy from place to place:
Radiation - Energy that travels distances in waves, can be absorbed or reflected.
Conduction – Transfer of heat energy from one substance to another by direct contact.
Convection – Transfer of energy by the motion of gas or liquid. Movement of gases up and down. Warm air rises, cool air sinks.
Example:
1. Radiation from sun warms the sand
2. Hot sand conducts energy to feet, air –or
anything that touches the sand
3. Warm air carries energy upward by convection

9. 1.3 - Gases in the Atmosphere pgs. 22-25
Atmosphere effects light in 4 ways:
Absorb light
Reflect light
Let it pass through
Give off light – emit light

10. 1.3 - Two types of radiation (energy):
1. Ultraviolet radiation – waves of energy you can’t see, causes sunburn.
2. infrared radiation – warms the materials that absorb it.

11. 1.3 - Earth’s Protection:
Ozone layer – ozone gases in the stratosphere, protects life on earth by absorbing harmful ultraviolet rays from sun.
Greenhouse effect – traps heat – absorbs gases (carbon dioxide, methane, etc.) and keeps earth warm – allows heat to go back into space.
Keeps Earth’s average surface temp. around 59 degrees.

12. Air Masses 3.1 – pgs
Air Mass – large body of air. covers thousands of miles.
Characteristics of Air Mass: depends on where it forms and the temperature
1st word tells where it forms (land or water)
2nd word tells temp. (near or far from equator)

13. Four Types:
Continental Tropical – dry and warm
Continental Polar – dry and cool
Maritime Tropical – moist and warm
Maritime Polar – moist and cool
Air Masses move from West to East – away from where they start.
Takes on characteristics of earth’s surface as it moves.

14. Front – boundary between air masses.
fronts are often cloudy or stormy
3 types:
Cold Front – cold air mass pushes a warm air mass. Produces cumulonimbus clouds. Brief heavy storms.
Cool weather
Warm Front – warm air mass pushes cold air mass.
Hours of rain or snow – warm air
Stationary Front – Two air masses push against each other and stop moving.
Becomes warm or cold when one air mass advances.

15. Storms: 3.2 – 3.3 pgs. 87 – 97 Storms – 3.2
High pressure system – can bring clear skies, calm air, gentle breezes
Low Pressure system – brings stormy weather
Tropical Storm – low pressure system that starts at the equator – winds 40 mph (65k)

16. Hurricanes Hurricane – low pressure system – winds 74 mph (120k)
Hurricane strike between Aug. thru Oct. – when water gets warm enough – loses strength when reaches land
Eye of Hurricane – center of storm, calm winds

17. Storm Surge – pushes huge mass of ocean water onto coastal area.
Winter storms result of two air masses colliding.
NWS – National Weather Service – alerts people to dangerous weather.

18. Blizzards – Blinding snowstorms, winds 35mph, occur in northern and central U.S.
Ice storms – rain falls onto freezing cold ground.
covers everything with ice

19. Severe Storms – 3.3 Lightning – spark of electricity
Air around lightning is heated briefly to temp. hotter than the surface of sun
Thunder – sharp wave of heated air that travels away from lightning

20. Thunderstorm – storm with lightning and thunder – get energy from humid air.
Effects of Thunderstorms:
Flash floods, winds, hail, lightning
Tornado – violently rotating column of air – occurs mostly in spring - unpredictable