homeI. View of planet Earth
A. Size of earth
1. Diameter 12,470 km
2. Circumference 40,074 km
3. Largest of inner planets
B. Features
1. Land (covers about 30% of Earth)
a. Solid layer known as crust
b. Includes 7 continents
C. Lithosphere
2. Water (covers about 70 % of Earth)
a. Hydrosphere
b. Salt water oceans (about 97%)
c. Fresh water lakes, rivers, streams, ponds (about 3 %)
d. Icebergs, glaciers
3. Air
a. Atmosphere
b. Oxygen and other gases
II. Development of atmosphere
A. Past atmosphere
1. Poisonous compounds
a. Methane
b. Ammonia
2. Sunlight caused chemical reactions
a. Nitrogen gas - greatest abundance
b. Hydrogen gas
c. Carbon dioxide
d. Water
3. Ozone layer
a. Combination of 3 oxygen atoms
b. 30 kilometers above Earth's surface
c. Absorbs harmful ultraviolet radiation
B. Present atmosphere
1. Nitrogen
a. Most abundant 78%
b. Used to make proteins
2. Oxygen
a. Second most abundant 21%
b. Used by living things
3. Carbon dioxide
a. Small amount
b. Used by plants
4. Water vapor
a. Weather conditions
b. Heats atmosphere
5. Solid particles
a. Mixed with gases
b. Dust, smoke, dirt, bits of salt
III. Layers of atmosphere
A. Troposphere
1. Layer closest to Earth
2. Height varies
3. Warmed by convection currents
4. Temperature decreases at higher altitudes
5. Tropopause
a. Temperature remains constant
b. Separates troposphere from stratosphere
B. Stratosphere
1. Extends to altitude of 50 kilometers
2. Extremely cold
3. Air not still
a. Jet streams
b. Move horizontally, eastward
4. Contains ozone
a. Shields Earth against ultraviolet radiation
b. Warms upper stratosphere
5. Stratopause
a. Highest temperature in stratosphere
b. Separates stratosphere from mesosphere
C. Mesosphere
1. Temperature drops to -100˚ C
2. Extends from 50 kilometers to 80 kilometers
3. Protects Earth from meteoroids
D. Thermosphere (heat sphere)
1. Extends 80 kilometers above Earth with no upper limit
2. Air very thin
3. Temperature very high 2000˚ C or more
4. Ionosphere
a. Lower thermosphere
b. Extends 80 to 550 kilometers
c. Size varies with amount of x-ray and ultraviolet radiation
d. Ions absorb radiation
5. Exosphere
a. Upper thermosphere
b. Extends 550 kilometers and beyond
c. Air very thin
d. Where satellites orbit
IV. Magnetosphere
A. Earth's magnetic force
b. Size depends on solar wind
c. Made up of positively charged protons and negatively charged electrons
d. Van Allen Radiation Belts