Download The Dynamic Earth Chapter 3

The Dynamic Earth
Chapter 3
The Earth as a system:
-The Earth is a system that is made of rocks, air,
water and living things that all interact with each
other.
Geosphere: All of the rock, soils and sediments
on the Earths surface.
Atmosphere: The mixture of gases that make up
the air we breathe
78% nitrogen, 21% oxygen, 1% trace gases
The hydrosphere: All of the water on the Earths
surface.
The Biosphere: Is the part of the Earth where life
exists. This ranges from the bottom of the oceans
to about 9 Km above the Earth’s surface.
Section 1: The geosphere
Discovering the Earth’s interior:
Scientists have used data from seismic waves
produced by Earth quakes in order to learn about
the inside of the earth.
Primary, or P waves go twice as fast as S waves
and can travel through solids and liquids (like the
liquid outer core).
Secondary or S waves arrive after the P waves
and are blocked by liquids (and can not travel
through the liquid outer core).
To find the
epicenter, you
need three stations
that recorded the
Waves.
Then you need to
find the difference
in P and S wave
arrival times.
Then use a chart
to find the
epicenter distance.
Then draw a
circle on a
map for each
station.
Where the
three circles
meet is the
location of the
epicenter.
This is called
Triangulation.
Composition of the Earth
• Scientists have divided up the Earth in to three
basic layers based on their chemical
composition.
• The Crust, Mantle and Core.
• Crust: Earths thin
rocky outer layer
made mostly of
lighter elements.
• Mantle: The rock
layer of medium
density that is
below the crust.
• Core: Inner most
layer composed
of the densest
elements.
Structure of the Earth
• The earth can be divided into 5 layers based on
physical properties.
• Lithosphere (Lithos is Greek for stone): Earth’s outer
layer of rock and is divided into large slabs called
tectonic plates.
• Asthenosphere (Asthenos is Greek for weak): is the
plastic like solid layer of rock beneath the lithosphere.
It flows very slowly and allows the tectonic plates to
ride on top.
• The outer core: Is a dense liquid layer of molten rock
(which blocks the S waves).
• The inner core is made of solid iron and nickel.
Plate Tectonics: The lithosphere is broken into large
slabs called plates. These plates move due to
convection cells in the mantle
• These plates interact with each other at plate
boundaries.
• There are three different types of boundaries.
• Convergent: Plates come together and form
subduction zones with ocean crust or mountains with
continental crust.
• Divergent: Plates are moving apart. This creates
ocean ridges, rift valleys.
• Transform: Plates move side by side.
Earthquakes!
• Fault: A break in the Earth’s crust along which blocks
of the crust slide relative to one another.
• Earthquakes: The vibrations caused by the
slippage along these faults.
• Richter scale: used to quantify the amount of energy
released by an earthquake.
• Magnitude: The measure of energy is called.
• For each increase of 1 on the scale represents 32
times more energy than the previous number.
Where do Earthquakes occur?
• Most earthquakes occur at plate boundaries.
• About 1 million occur each year but most can’t be felt.
• There is a direct relationship between earthquakes
and volcanoes.
Volcano: A mountain
built from magma,
that rose from the
Earth’s interior to
the surface.
Local effects of Volcanic
Eruptions:
• Loss of life
• Destruction of
property
• Loss of income to
local economy
• Loss of tourism
Global Effects of Volcanic Eruptions:
• Can cool the earths climate for years due to the ash
cloud reducing how much sunlight gets through.
• This can reduce the amount of sunlight by 2-4% and
can reduce the global temp by nearly a degree.
Erosion: The removal and transport of Earth’s surface
material.
• Weathering: The break down of Earth materials.
• Water erosion: Rivers and oceans move millions of
tons of sediment each year and dramatically change
the landscape over time.
Wind Erosion: Wind carries away particles in areas of
little vegetation like beaches and deserts.
Glaciers: Large moving mass of ice.
• This is responsible for most of the lakes in NY.
• Creates U shaped valleys.
• Can leave large deposits such as Long Island
Section 2: The Atmosphere
Composition: 78% Nitrogen, 21% Oxygen, 1% other
Atmospheric functions:
• Allows us to breath.
• Insulates the Earth and regulates temperatures
• Distributes energy
• Protects us from harmful UV rays (ozone layer)
Air pressure: Caused by the weight of the ocean of air
above us. The higher you go, the less air is on top
of you, there for the less air pressure.
Layers of the Atmosphere
• Troposphere: Layer closest to the Earth’s surface.
• This is aka the “Weather sphere” because this is
where the storms occur. This layer has the most
humidity
• Extends to 18 Km
•
This layer is the most dense
• Temperatures decrease with altitude
Stratosphere: The layer above the troposphere.
• Temperature rises as you increase in elevation.
• Contains the ozone layer
• Extends from 18 Km to 50 Km
Mesosphere: The layer above the Stratosphere.
• Extends up to 80 Km
• Coldest layer of the atmosphere (-93 C)
Thermosphere: The atmospheric layer farthest from the
Earth’s surface.
• The temperatures go up with altitude due to the
nitrogen and oxygen absorbing radiation.
• Temps here can reach 2000 C but it wont feel warm
to us because the molecules are so far apart.
Energy in the Atmosphere
Energy can be transferred in 3 ways.
1. Radiation: The transfer of energy across space and in
the atmosphere
• Ex heat from the Sun, or fire.
2. Conduction: Is the flow of heat from a warmer object
to a colder one.
3. Convection: The transfer of energy through fluids
(gases or liquids).
Heating of the Atmosphere
• Solar energy reaches earth as electromagnetic
radiation traveling at 186,000 miles/sec
• 50% of the solar energy that hits the atm reaches the
surface
• The other 50% gets absorbed or reflected
The Movement of energy in the Atmosphere
• Air flows from areas of High pressure to low
pressure.
• This is caused by differences in temperatures
• Hot air rises spreads and sinks as cold air.
• These form convection currents.
Greenhouse Effect
• After sunlight (short waves) hits the earth surface it
bounces back as infrared (long waves).
• These longer waves can’t penetrate the atmosphere
because they are trapped and reradiated back to
Earth by the greenhouse gases.
The main greenhouse gases are carbon dioxide and
methane, water vapor and nitrous oxide.
Greenhouse gas sources
Section 3: The Hydrosphere and Biosphere
The Hydrosphere and Water cycle
Water cycle: The continuous movement of water into the
air, onto land, and then back to water sources.
Evaporation: Is the process by which liquid water is
heated by the Sun and rises into the atmosphere as
water vapor.
Condensation: When water vapor cools and becomes a
liquid.
Precipitation: When
water droplets fall
because they are
too large to be held
up in the cloud.
Transpiration: When
the water given off
by trees and plants
evaporates.
Earth’s Oceans
• World Ocean: The Atlantic, Pacific, Artic, and the
Indian oceans are all interconnected.
• This covers a little more than 70% of Earths surface.
Pacific Ocean
• Largest ocean
• Deepest point is called Challenger Deep which is at
the bottom of the Mariana Trench (11,033 m)
• This is deeper than Mt Everest is tall (8,800 m)
• James Cameron went down there in a mini sub.
Atlantic Ocean
• Second largest ocean
• ½ the size of the Pacific ocean
• Charles Lindberg made famous by becoming the
first pilot to make the flight across the Atlantic.
Indian ocean
• Third Largest ocean
Artic Ocean
• Smallest ocean
• Much of the surface is
covered with ice
Ocean water
• More dense then fresh
water due to more salt
• Salinity: concentration of
dissolved salts it contains
Temperature zones
• The surface water is warmed by the Sun.
• The depths are cold because sunlight cant reach.
• Thermocline: Depth of 300 M to 700 m where the
temp decreases rapidly with depth.
A Global temperature regulator:
• The oceans absorb and store energy from sunlight.
• This regulates temps in the atmosphere.
• The Worlds ocean absorbs over 50% of the radiation
that reaches the surface.
• Cities near the ocean have milder annual temps
Water has a higher specific heat than land.
• Water takes a long time to heat up and a long time
to cool down.
• This helps regulate the temps in the atm as well.
• Without the oceans, the temps on Earth would be
too extreme for life to survive.
Ocean currents
• Currents are created by wind, differences in temp
and density.
• Currents redistribute heat throughout the oceans.
• If currents like the North Atlantic drift were to shut
down it could throw Europe into an ice age.
Fresh Water
• About 3% Of all of the water on Earth is fresh.
• 90% of that 3% is locked away in the ice caps.
• Most of the useable fresh water is underground
River Systems or water sheds
• A network of streams and rivers that drains an area
of land.
• Tributaries: are smaller streams and rivers that flow
into larger ones.
• The Mississippi is the largest water shed in the
contiguous United States.
Ground Water
• When water
infiltrates the
ground it becomes
ground water.
• Aquifer: A rock
layer that stores
and allows the
flow of ground
water.
• Recharge zone:
The surface of the
land where water
enters the aquifer.
Biosphere: The Narrow layer
around Earth where life
can exist.
Requirements for life:
1. Water
2. Temps between 0 and
40 degrees C
1. Source of energy
Most life is near the Earths
surface because this is
where the sunlight is.
Energy Flow in the Biosphere
• Energy from the Sun is constantly being added to
the biosphere but matter is not.
Food chain
• When an organism dies, its body is used by other
organisms for substance. When the top predators
die, their bodies are broken down by fungus and its
nutrients become available for other organisms to
use.
Closed system: Energy enters the environment, but
mater does not. The Earth is mostly a closed
system.
Open system: Both mater and energy are exchanged
between a system and the surrounding environment.
The early Earth was hit frequently with comets and
meteorites, so was more open than it is today.