Download Unit 1 Ch. 3 Intro to env Science

Ch. 3 The Dynamic Earth
UNIT 1 CH. 3 INTRO TO ENV SCIENCE

Earth is a system with 4 parts
 Geosphere
– rock
 Atmosphere – air
 Hydrosphere – water
 Biosphere – living things
 These
4 parts are constantly
causing the earth to change.
THE GEOSPHERE

Composition of the earth – 3 layers
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Crust – outer layer, thin, made of lighter
elements
Mantle – middle layer, medium density
rocks
Lithosphere – rigid outer layer made of
tectonic plates
 Asthenosphere – layer of rock that flows
very slowly allowing the tectonic plates to
move on top


Core – innermost layer of dense
elements
Outer core – liquid nickel and iron
 Inner core – solid nickel and iron
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PLATE TECTONICS
Lithosphere divided into pieces called plates
 Plates float on top of the asthenosphere
 Continents are on top of plates and move with
them
 Plate boundaries – site of geological activity
when plates collide, move away from or slide
along each other

 Causes
mountain building, earthquakes, and
volcanoes
PLATES OF THE WORLD
EARTHQUAKES
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Fault – break in the earth’s crust where blocks of the crust
slide along each other
Rocks (blocks) slip due to stress sending out vibrations of
energy through the earth’s crust causing an earthquake
Magnitude – measure of energy released by an earthquake

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Richter scale – 1 to 14 – measure of 7 = widespread damage
Where? – along plate boundaries
Can’t predict when, but can label hazard areas
VOLCANOES
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Volcano – mountains
built by magma,
rises from inside the
earth to the surface
Located along plate
boundaries

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Ring of Fire –
around pacific
ocean
Effects: human loss,
building destruction,
crop destruction,
mudflows, breathing
difficulties, can
cause climate
changes
EROSION
Erosion – removal and
transport of surface materials
 Caused by wind and water
 Changes the shape of rocks
and landscape – softer rocks
erode more quickly
 Applachian mtns = rounded
tops = older
 Rocky mtns = jagged =
younger

3.2 THE ATMOSPHERE
Mixture of gases surrounding the
earth
 Keeps the earth warm so living
things can survive
 Gases constantly put in and taken
out
 Composition

Nitrogen 78%
 Oxygen 21%
 Other 1%
 Atmospheric dust


Air Pressure – atmosphere more
dense near surface due to gravity
LAYERS OF THE ATMOSPHERE

Based on temp changes
Troposphere – nearest to the
surface, where all the weather
occurs, temp ↓ as altitude ↑
 Stratosphere – temp ↑ as
altitude ↑ because ozone is
absorbing uv rays from the
sun
 Mesosphere – coldest layer
 Thermosphere - contains the
auroras

ENERGY IN THE ATMOSPHERE

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Energy comes from the sun
Transferred in 3 ways

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
Energy comes into atmosphere
from sun
Radiation – rays through space
Conduction – objects touching
Convection – by air currents –
circulates heat through
atmosphere
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Some is reflected by earth’s
surface
Some is absorbed by earth’s
surface (1/2)
Some is scattered by clouds
and air
Some is absorbed by clouds
Earth’s surface radiates
heat back into atmosphere

Heat absorbed by greenhouse
gases keeping the earth warm
GREENHOUSE EFFECT
Process in which gases trap heat near the
earth
 Life could not exist on earth without GE

3.3 THE HYDROSPHERE
All water on or near the earth’s surface
 Required for life
 The water cycle – continuous movement of
water into the air, onto land and back to water
sources

 Evaporation
– liquid to gas – ground to air
 Condensation – gas to liquid – water forms droplet
on dust particle – forms clouds
 Precipitation – water falling from clouds
THE WATER CYCLE
OCEANS
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World ocean – interconnected body of all the
oceans
Covers 70% of earth’s surface
Made of: Pacific, Atlantic, Indian, Arctic
Ocean water: contains more salts than
freshwater
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Salinity – concentration of salts (avg. = 3.5%),
different for different parts of the ocean
Temperature zones – warmer at the surface,
colder in deep water
Function of world ocean – regulates
temperatures in the atmosphere

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Ocean water absorbs radiation from the sun
and releases heat (more slowly than land)
Temp of atmosphere changes more slowly
because of the ocean
OCEANS CONT.

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Ocean currents – stream like movements of water
through the ocean, can be warm or cold, at the surface
or deep
Warm water won’t mix with cold so the currents can
travel a great distance where they influence local
climates on land
FRESHWATER
30% of hydrosphere –
most is frozen in glaciers
and icecaps, the rest is in
rivers, lakes, wetlands,
and the ground
 River system – network of
streams that drain an
area of land
 Groundwater – water
stored underground in
rock or soil (aquifers)

THE BIOSPHERE
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Narrow layer around the earth’s
surface in which life can exist
Includes uppermost part of geosphere,
most of the hydrosphere, and the lower
part of the atmosphere
Fulfills 3 requirements for life:

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Liquid water, moderate temps, energy
source
Energy flow

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Closed system – energy comes in and
goes out so it must be constantly
supplied
Matter is recycled through the system