Unit 12Integrated Science

Planet EarthI. Layers of the Earth

A. Spheres1. Earth is made of 4 layers that interact w/ each other

a. Atmosphere 1) layer of air surrounding the Earth

b. Hydrosphere1) all the water on Earth

c. Biosphere1) all the living organisms on Earth

d. Lithosphere1) solid rock part of Earth2) incl. mountains, valleys, continents, rock beneath

oceans

B. Earth’s Atmosphere1. only atmosphere in our solar system that can currently

sustain lifea. about 480 km thick

1) most is w/in 16 km of Earth’s surface2) creates air pressure pushing on Earth’s surface

a) 14.7 pounds per square inch at sea levelb) 10 pounds per square inch at 3 km above sea

level1)) less breathable oxygen at this level

b. it’s a blanket of gases surrounding planet1) mostly nitrogen (78%) and oxygen (21%)

a) rest = carbon dioxide & argon and other gases in trace amount

2) also contains up to 4% water vapora) amount varies depending on locationb) creates humidity in air

3) the greenhouse gases protect Earth from Sun’s heat & radiationa) incl. carbon dioxide, methane, water vapor &

ozoneb) regulate planet’s surface temperature

2. Atmosphere has 5 main layersa. troposphere {Tropos – (L) change}

1) closest to surface2) 7-20 km thick depending on location

a) thinnest at each pole3) contains ½ of Earth’s atmosphere

a) incl. breathable air, clouds4) ¾ of the entire atmosphere’s mass

b. stratosphere {Strata – (L) layer}1) above troposphere to about 50 km above

grounda) about 35 km thick

2) contains the ozone layera) heats atmosphere, absorbs solar (UV) radiation

3) air is dry & very thin herea) jets & weather balloons fly in this layer

4) has its own set of layersa) cold, heavy air at the bottomb) warm, light air at the top

c. Mesosphere {Meso – (L) middle}1) 50 – 85 km above Earth’s surface2) highest layer in which all the gases are still mixed

together3) its top – the mesopause – is the coldest part of

the atmospherea) avg. -90o C

4) air here is too thin to breathe5) meteors burn up in this layer

a) enough gases here to cause friction & create heat

d. Thermosphere {Thermos – (L) heat}1) 90 km to between 500-1000 km above Earth2) 2nd thickest atmosphere layer

a) low density b) often thought of as space

3) temperatures up to 1500o Ca) however, you’d feel cold because molecules

don’t move fast enough here to transfer heat4) not enough molecules for sound to travel through5) Int’l Space Station & low-atmosphere satellites orbit

in this layer

e. Exosphere {Exo – (L) outer}1) thickest layer of atmosphere – about 10,000 km

a) nearly as wide as Earth itself2) separates atmosphere from outer space3) thinnest air

a) mainly particles of hydrogen & helium w/ much empty space between them

b) very cold

f. additionally, the ionosphere can be identified1) overlaps mesosphere, thermosphere & exosphere2) grows / shrinks depending on energy absorbed

from suna) gases here are excited by solar radiation to

form ions3) overlaps Earth’s magnetosphere

a) area around Earth where ions feel its magnetic field

4) auroras occur in this range

C. Earth’s Interior 1. Earth has a solid surface and layered interior

a. four distinct layers1) Crust, Mantle, Outer Core & Inner Core2) crust & rigid, upper part mantle combine to

form the lithosphere {Greek - lithos = rock}a) extends down about 100 kmb) broken into about a dozen tectonic plates

1)) move in relation to each other 1-10 cm per year

c) incl. continental crust & oceanic crust

2. The Crusta. outermost, relatively thin layerb. incl. oxygen, silicon, aluminum, calcium, sodium,

potassium & magnesiumc. about 1% of Earth’s massd. two types

1) Oceanic crust - beneath oceans & seasa) 5-8 km thick, younger

2) Continental crust - thicker & less densea) 20-40 km thick, olderb) even deeper below mountains (70+ km thick)

3. The Mantlea. mostly solid layer of rock

1) mostly silicate rocks w/ magnesium & iron2) more viscous at tectonic plate boundaries &

mantle plumesb. about 2900 km thickc. about 80% of Earth’s volumed. denser than the cruste. temp ranges: 1000oC near crust - 3000o C near coref. volcano eruptions = mantle pushing through crust

f. includes the asthenosphere 1) below lithosphere

a) 80-200 km below surface2) solid rock layer, but high temps & high pressure allow

rocks to flow like a liquida) rocks are less dense than in lithosphereb) rocks are more “plastic”- soft & easily deformedc) allows tectonic plates above to “float” around

Earth’s surface

4. The Outer Corea. liquid metal alloy of nickel & iron

1) pressure due to mantle & crust’s weight prevents them from becoming gaseous

2) flows in currents3) its churning creates Earth’s magnetic field

b. about 2180 km thickc. easily deformed & highly malleabled. temps = 4500-6000o C - as hot as surface of the Sun

5. The Inner Corea. solid dense ball of mostly iron

1) some scientists describe it as plasma behaving like a solid

2) pressure here is so great it forces atoms together as solids despite high temps

3) pressure = nearly 3.6 million atmb. radius = about 1220 kmc. temp = about 5200o Cd. Planet Earth is older than the inner core by about

500 million years

e. rotates a little faster than rest of Earth1) has an extra rotation avery 1000 years2) contributes to Earth’s magnetic field

f. as Earth cools, inner core grows1) about 1 mm each year2) occurs when bits of liquid outer core crystallize3) grows unevenly - more in subduction zones

a) where tectonic plates are slipping into mantle