Earth Science
NHSPE Preparation and Tutoring
3 Main Topics
• Atmospheric Processes and the Water
Cycle
• Solar System and Universe
• Earth’s Composition and Structure
1. Atmospheric Processes and
the Water Cycle
• The Sun is the major source of Earth’s energy, and provides the energy
driving Earth’s weather and climate.
• The composition of Earth’s atmosphere has changed in the past and is
changing today.
• The greenhouse effect is an essential process to maintaining a habitable
temperature range on Earth.
• Convection and radiation play important roles in moving heat energy in
the Earth system.
• Earth’s rotation affects winds and ocean currents.
Interactions-Sun and Earth
• More than 99% of the Earth’s energy comes from the Sun
through visible light.
• The Earth also sends energy back into outer space, mostly as
infrared radiation.
• On average, this transfer of this incoming and outgoing energy
is nearly equal.
• Of the Sun’s incoming energy:
• --about 30% is reflected back to space.
• --another 19% of the incoming solar energy is absorbed by the
Earth’s atmosphere and clouds.
• --the remaining 51% is absorbed by the Earth’s surface.
Energy – From Earth to
Where?
•
To maintain equilibrium, the Earth returns the energy it receives from the Sun back
to space as infrared light.
• Only 6% of the energy goes directly from the Earth’s surface to space.
• About 15% of the Earth’s surface energy is absorbed by water vapor, carbon dioxide
and other gases in the atmosphere. (greenhouse effect)
•
The remainder of Earth’s surface energy is transferred to the atmosphere in a more
complex exchange involving sensible and latent heat.
• Sensible heat is the energy associated with the temperature of a body. A warm surface
will be at a higher temperature. Sensible heat flows from the surface to the atmosphere
via convection (air circulations) or conduction (molecular motion).
• Latent heat is the energy associated with phase changes. In the atmosphere, water
vapor condenses forming clouds and precipitation. This releases latent heat to the
atmosphere. Latent heat also flows from the atmosphere to the surface during
evaporation. Evaporation cools the atmosphere.
•
So, infrared radiative transfer combined with flux of sensible and latent heat
provides the energy to the atmosphere. This energy, which ultimately originated
from the Sun, drives all of Earth’s weather and climate.
What Does The Sun Energy
Do On Earth?
• Powers the water cycle. (and many of the other
biochemical cycles).
• Warms the atmosphere and surface
• Drives weather and climate through the uneven
heating of the Earth’s surface.
• Provides needed energy for photosynthesis in plants
Diagram It!
The Water Cycle
• Water: essential for life on earth. It is recycled
through the water or hydrologic cycle.
• Amount of water on earth remains nearly constant and
is continually recycled through time.
• Water molecules may remain in one form for a very
long period of time and in other forms for very short
times.
• Remember, this is all driven by energy from the sun!
Water Cycle Processes
• Evaporation: changing of water from a liquid to a gas
• Condensation: changing of water from a gas to a liquid
• Sublimation: changing of water from a solid to a gas
• Precipitation: water molecules condense to form drops
heavy enough to fall to the earth's surface
Water Cycle Processes
• Transpiration: moisture is carried through plants from roots to
leaves, where it changes to vapor and is released to the
atmosphere
• Surface runoff, the flowing of water over the land from higher
to lower ground
• Infiltration: the process of water filling the porous spaces of
soil
• Percolation: groundwater moving in the saturated zone below
the earth's surface
Diagram It!
Atmosphere –
Its Role
• Atmosphere Role: protects the Earth’s surface from
the sun’s radiation and helps regulate the
temperature of the Earth’s surface.
• What is the atmosphere?
• A mixture of gases the surrounds a planet.
• All weather on Earth occurs in the atmosphere and
it is essential to life.
Atmosphere Composition
• Composition of the atmosphere:
•
•
•
•
•
Nitrogen
Oxygen
Carbon dioxide
Other gases
Water vapor (variable)
78%
21%
0.03%
0.17%
1-3%
Layers of the Atmosphere
(The Most Important Ones)
• Troposphere: closest to the Earth’s surface and where weather
occurs. You can find the majority of the water vapor and
carbon dioxide here (hey, it’s the greenhouse glass!)
• Stratosphere: from the top of the troposphere (known as the
tropopause) to altitude of 50km. Ozone lives here (well almost
all of it).
• Mesosphere: from the stratopause (the top of the stratosphere)
to altitude of 80km. Coldest temperatures in the atmosphere!
• Thermosphere: Almost to the top. The only thing beyond is
the ionosphere (aurora borealis zone) and exosphere (transition
to space). Nitrogen and oxygen absorb solar radiation here.
Greenhouse Gases and the
Greenhouse Effect
• Greenhouse gases: carbon dioxide, methane, water
vapor
• Importance of greenhouse gases: these gases help
keep some of the radiation from going back to space.
They help regulate the temperature of Earth and
keep it habitable for life.
• Note: Interference from humans can cause increases
of greenhouse gases in the atmosphere. When this
happens, the Earth may get too hot!
Sources of Greenhouse Gases
• Naturally through the biochemical cycles (Water
cycle, carbon cycle, nitrogen cycle, etc), volcanes, etc.
• Human interference through CFC emissions and
industrial activities.
Atmosphere & Ocean
•
Oceans cover nearly three-quarters of the earth's surface and play
an important role in exchanging and transporting heat and
moisture in the atmosphere.
•
Most of the water vapor in the atmosphere comes from the oceans.
•
Most of the precipitation falling over land finds its way back to
oceans.
•
About two-thirds returns to the atmosphere via the water cycle.
•
You may have figured out by now that the oceans and atmosphere
interact extensively. Oceans not only act as an abundant moisture
source for the atmosphere but also as a heat source and sink
(storage).
Atmosphere-Ocean
• Ocean currents play a significant role in transferring
this heat poleward. Major currents, such as the
northward flowing Gulf Stream, transport
tremendous amounts of heat poleward and
contribute to the development of many types of
weather phenomena. They also warm the climate of
nearby locations. Conversely, cold southward
flowing currents, such as the California current, cool
the climate of nearby locations.
Energy Heat Transfer
• Energy is transferred between the earth's surface and the
atmosphere via conduction, convection, and radiation.
• Conduction: process by which heat energy is transmitted
through contact with neighboring molecules.
• Convection transmits heat by transporting groups of
molecules from place to place within a substance. Occurs
in fluids such as water and air, which move freely.
• Radiation: the transfer of heat energy without the
involvement of a physical substance in the transmission.
Radiation can transmit heat through a vacuum.
Diagram It!
Conduction
• Air and water are relatively poor conductors.
• Most energy transfer by conduction occurs right at
the earth's surface.
• At night, the ground cools and the cold ground
conducts heat away from the adjacent air.
• During the day, solar radiation heats the ground,
which heats the air next to it by conduction.
Convection
• In the atmosphere, convection includes large- and
small-scale rising and sinking of air masses and
smaller air parcels.
• These vertical motions effectively distribute heat and
moisture throughout the atmospheric column and
contribute to cloud and storm development (where
rising motion occurs) and dissipation (where sinking
motion occurs).
Convection Cells
• Convection cells distribute heat over the whole earth.
•
Consider a simplified, smooth earth with no land/sea
interactions and a slow rotation. Under these conditions, the
equator is warmed by the sun more than the poles. The warm,
light air at the equator rises and spreads northward and
southward, and the cool dense air at the poles sinks and spreads
toward the equator. As a result, two convection cells are formed.
• Meanwhile, the slow rotation of the earth toward the east
causes the air to be deflected toward the right in the
northern hemisphere and toward the left in the southern
hemisphere. This deflection of the wind by the earth's
rotation is known as the Coriolis effect.
Diagram It!
Radiation
• Energy travels from the sun to the earth by means of
electromagnetic waves.
• The shorter the wavelength, the higher the energy
associated with it.
• Most of the sun's radiant energy is concentrated in
the visible and near-visible portions of the spectrum.
Shorter-than-visible wavelengths account for a small
percentage of the total but are extremely important
because they have much higher energy. These are
known as ultraviolet wavelengths.
2. Solar System and Universe
• Stars: The most important characteristics to know are color,
temperature, mass, and luminosity.
• Stars are powered by nuclear fusion of lighter elements into
heavier elements, which results in the release of large amounts
of energy.
• Technology has increased understanding of the universe.
• Study of the ongoing processes involved in star formation and
destruction help us to understand what is happening in our
Sun.
•
Scientific evidence suggest that the universe is expanding.
Stars: Color and Temperature
• Most stars appear white to our eyes, however, the
predominant color is dependent upon their surface
temperature.
• The hotter the star, the more blue light it emits;
conversely, cooler stars emit more red light
• If different colors are emitted with each about the same
intensity, the star will appear white.
• Note that these temperatures, though much hotter than
what we encounter in our lives, are still quite small
compared to the temperature at the star’s core (which can
be tens to hundreds of millions of degrees!)
Stars: Mass
• Mass: the most important characteristic and
determines the life span and ultimate fate of a star.
• The lower the mass, the longer the life span. The
higher the mass, the shorter the life span.
• Example: Our Sun, 1 solar mass = 10B years.
Another star, 30 solar mass = 15M years
• Ultimate fate: Low mass = red giant, planetary
nebula, white dwarf. High Mass =
Giant/Supergiant, supernova, black hole, neutron
star
Stars: Luminosity
•
Luminosity: total amount of energy emitted by star every second.
•
Diameter and temperature determine luminosity.
•
Diameter determined by mass.
•
A star’s luminosity and temperature are frequently plotted on a graph
called the Hertzsprung-Russell, or H-R, Diagram.
•
Temperature (or sometimes its spectral class, which is related) is plotted on
the horizontal axis, with the values decreasing to the right.
•
Luminosity is plotted on the vertical axis, using a logarithmic scale.
•
When the corresponding values for a large number of stars are then
plotted on this graph, groupings of stars can be easily identified, including
the main sequence.
Nuclear Fusion?
• The primary source of energy in our Sun and all stars is
nuclear fusion.
• Four hydrogen ions (simply protons) are combined
through collisions to create one helium ion (containing
two protons and two neutrons).
• The high temperatures and densities required for nuclear
fusion can be found in the cores of stars.
•
The gravitational attraction between the gas particles
pulls them into a very small region and causes them to
move incredibly fast.
Nuclear Fusion?
• The fusion of hydrogen into helium constitutes what
astronomers call the star’s “main sequence” lifetime
• The most massive stars undergo fusion at an
extremely high rate, and so use up their fuel very
quickly – thus existing on the main sequence for a
shorter length of time than less massive stars.
• After the main sequence phase, helium can also
undergo nuclear fusion, as can other elements.
Space Technology
•
The telescope is humankind’s single greatest technological step toward
understanding our universe.
•
Galileo: made five important observations that directly contradicted the
mythological view of our universe:
• discovering that Jupiter has moons that rotate about the planet;
• observing that Venus has phases, a finding that could only be explained by
Venus orbiting the Sun;
• discovering that the Moon has mountains, valleys, and craters that are
similar to features on Earth;
• observing that the Sun has blemishes (sunspots) and rotates about once
every month; and
• observing that the Milky Way is not a smooth field of light, but is made
up of thousands of stars.
Space Technology
• Telescopes:
• observe light and it is through this light that scientists gather
all their information about the universe beyond Earth.
• The first telescopes, But visible is only a small part of the
entire light spectrum.
• In the 20th century, scientists began to use all other
frequencies of the electromagnetic spectrum (radio,
microwave, infrared, ultraviolet, x-ray, and gamma-ray)
• By observing these wavelengths, astronomers were able to
discover a vast universe of phenomena, such as black holes,
neutron stars, extrasolar planets, and active galaxies.
Hubble Space Telescope
•
Space-based observatories.
•
No atmospheric filter
•
Some light frequencies, such as infrared, x-ray, and gamma ray, are
only observed from space (or high in Earth’s atmosphere) because
these frequencies do not penetrate to Earth’s surface.
•
Hubble Space Telescope is the most famous and has provided a
view of the universe in the visible and ultraviolet light that has not
yet been equaled from much larger Earth-based telescopes.
•
Chandra X-ray Observatory and the Spitzer Space Telescope, have
been equally as important to science as Hubble because they
provided very high-resolution views of our universe in frequencies
outside the visible.
Star Life Cycle
• http://www.bighistoryproject.com/~/media/Files/
BigHistory/Star%20Stages%202012-03-20.pdf
• How does this work? Gravity.
• A star must maintain equilibrium and offset gravity
by the energy that it pushes outward.
• Main sequence: A star is fusing hydrogen into
helium.
Expanding Universe
• Early 1920s, an astronomer at Mount Wilson
Observatory named Edwin Hubble
• Hubble observed that the spectral signatures of almost all
galaxies were redshifted, indicating that they were
moving away from Earth.
• Furthermore, the farther away the galaxy is, the greater
its redshift. In other words, galaxies were moving away
from Earth at a rate proportional to their distance from
us. This relationship is now called Hubble’s Law and is
an indication that the universe is expanding.
3. Earth’s Composition &
Structure
• Diagram
Objectives
•
Objective 1: Students know how successive rock strata and fossils can be used to
confirm the age, history, and changing life forms of the Earth, including how this
evidence is affected by the folding, breaking, and uplifting of layers.
•
•
•
•
•
•
Explain the basics of the process of fossil formation.
Apply the principles of superposition to relative dating of rock layers.
Describe the process of absolute dating.
Sequence the age, history, and changing life forms of Earth using strata and fossil evidence.
Describe how folding, breaking, and uplifting of strata complicate geological evidence.
Objective 2: Students understand the concept of plate tectonics including the
evidence that supports it (structural, geophysical and paleontological evidence).
• Describe how convection in Earth’s mantle has changed the locations + shapes of continents based
on tectonic plate movement.
• Identify the evidence for seafloor spreading.
• Identify the three major types of tectonic plate boundaries.
Objectives
•
Objective 3: Students know elements exist in fixed amounts and move
through solid earth, oceans, atmosphere and living things as part of
biogeochemical cycles.
• Explain how matter and energy are transferred chemically through systems that include
living and non‐living components.
•
Objective 4: Students know processes of obtaining, using, and recycling of
renewable and non‐renewable resources.
• Identify the differences between renewable and non‐renewable resources.
• Explain how recycling reduces the rate of depletion of nonrenewable resources.
• Identify the processes used to obtain natural resources (e.g., mining, oil production, water,
and agriculture).
•
Objective 5: Students know soil, derived from weathered rocks and
decomposed organic material, is found in layers.
• Describe the structure of soil, its components, and its formation
Key Ideas
Fossils
• Different rock layers contain different fossils (key to
dating the geologic past)
• Fossils: the remains of animals or plants that lived in
a previous geologic time
• Paleontology: the study of fossils
• Fossils provide information to the relative and
absolute ages of rocks, as well as provide clues to
past geologic events, climates, and evolutiom
Fossilization
• Generally, only the hard parts of organisms become
fossils. Fossilization processes are:
•
•
•
•
•
Mummification
Amber: hardened tree sap
Tar Seeps
Freezing: almost completely preserved
Petrification: replica of the original organism
Fossil Types
• Trace fossil: a fossilized mark that formed in sedimentary
rock by the movement of an animal on or within soft
sediment
• Index fossil: fossils that occur only in rock layers of a
particular geologic age (used to determine the relative age
of rock layers)
• Must be present in rocks scattered over a large region
• Must have features that clearly distinguish it from other
fossils
• Organism must have lived during a short span of geologic
time
• Must occur in fairly large numbers within the rock layers
Rock Cycle
• Rocks: naturally occurring aggregates of one or more
minerals.
• Composed of material that has been present on Earth since it
first formed – excluding that material which has been
delivered by meteorites
• Rock Cycle: a model that illustrates the changes to rocks
that have taken place through time.
• Rocks are recycled into other rocks through processes which
occur in mainly two locations; at or near Earth’s surface such
as weathering, erosion, and deposition; and deep below the
surface such as melting and increased heat and pressure.
Most rocks are formed from other rocks and a “rock” may
take more than one path through the rock cycle.
Diagram It!
Rock Cycle and Rock Types
Metamorphic rock: metamorphic rock would need to experience an increase in
temperature to the point of melting it, creating magma.
•
•
Eventually this magma body would enter an environment where the heat contained would
transfer from it (cooling) and the process of solidification (crystallization) occurs. This rock is
now classified as an igneous rock.
Igneous rock: several more changes must occur in order to turn this igneous rock into a
sedimentary rock.
•
•
The igneous rock needs to be subjected to the agents of weathering and erosion, which over
geologic time creates pieces or fragments of rock called sediment. As this sediment piles up,
compaction and cementation turn the loose sediment into a solid rock through the process of
lithification. This rock is now classified as a sedimentary rock.
•
Continuing clockwise this sedimentary rock will become a metamorphic rock with the
addition of heat and pressure causing a partial melting of some of the minerals in the
sediment. This process is referred to as metamorphism and results in creation of a
metamorphic rock. The straight arrows within the rock cycle diagram indicate that any one
rock type can turn into any other rock type by passing through several common processes.
Rocks and Minerals
• Key Points:
•
•
•
•
•
Fossils
Superposition
Absolute dating
Rock Types
Mineral Information
External Forces
• Processes that wear the Earth’s surface down
• 1. Weathering: the breaking down of rocks into
smaller pieces (assists in the formation of soil)
• Physical weathering
• Chemical weathering
• 2. Erosion: the process by which rock material at
Earth’s surface is removed and carried away
• Gravity and water
• Glacier
• Wind
Physical Weathering
• Rock is broken into smaller fragments by physical
agents
• Example: water seeps into cracks, in a rocks and
freezes, the water expands, breaking the rock apart
• Example: roots of plants growing in cracks can also
force rocks apart
Check for Understanding
Chemical Weathering
• The breaking down of rocks through changes in
their chemical make-up
• Changes take place when rocks are exposed to air or
water
• Example: rainwater + carbon dioxide = weak acid
that dissolves certain minerals in rocks causing rocks
to fall apart
• Example: oxygen + water + iron in rocks = iron into
rust, crumbles easily
Erosion
• Gravity and water: gravity moves water downhill,
running/flowing water erodes rock material
• Example: Grand Canyon
• Glaciers: masses of ice that from in places where more
snow falls in winter than melts in summer
• Glacier moves downhill slowly, grinding and removing rock
material
• Wind: dry desert areas, sand grains blown along by the
wind scrape and scour rock outcrops, slowly carving
them into unusual shapes
Check for Understanding
• Erosion is the process by which rocks at the Earth’s
surface
•
•
•
•
A. Are removed and carried away
B. Crumble and decay
C. Turn into rust
D Melt to form magma
Internal Forces
• Processes that shape the Earth’s surface. Produces:
• Mountains: produced by faulting and folding
• Earthquakes: produced by strong vibrations along faults
• Volcanoes: a hole in Earth’s crust through which lava flows
from underground; lava cools to form solid rock
• Plains: broad flat regions found at low regions; often made
of layered sedimentary rocks that were formed underwater
and slowly raised above sea level
• Plateaus: large areas of horizontally layered rocks with
higher elevations than plains; formed by either a large block
of crust rising up along faults, or being gradually uplifted
without faulting, or built up by lava flows
Folding
• Forces in Earth’s crust press rocks together from the
sides, bending the layers into folds. The land is
squeezed into upfolds and downfolds, forming ridges
and valleys.
Faulting
• Occurs when forces in the crust squeeze or pull rock
beyond its capacity to bend or stretch. The rock
then breaks and slides along a crack or fracture,
called a fault, relieving the stress in the crust
Plate Tectonics
• Theory that explains how internal forces that shape the
Earth’s crust move and work.
• Movements cause mountain building, volcanic activity,
and earthquakes along the plate edges
• Earth’s crust is divided into multiple plates that slowly
move.
• Divergent plates: plates that are moving away from each
other
• Transform plates: plates that are sliding past each other
• Convergent plates: plates that collide
Plate Tectonics
How Plate Tectonics Work
• Plate motions caused by heat circulating in Earth’s
mantle (the thick zone of rock beneath the crust)
How Plate Tectonics Work
• Continental plate collision produces mountain
ranges (ex. Himalayas)
• Plates sliding past each other produce fault zones
and earthquakes (ex. San Andreas Fault)
• Plates spreading apart produce ocean basins
• Continental drift: large continents are broken into
smaller landmasses that move away from each other.
• (Have you ever heard of Pangaea?)
Ocean Floor Features
•
Mid-ocean ridge: a long underwater mountain chain where rising
magma forms new ocean crust; new crust is added to crustal plates
that spread away from the ridge (seafloor spreading)
•
Trenches: underwater valleys that from the deepest part of the
ocean floor; found where where a plate of ocean crust collides
with another plate and is forced to slide under it, back into Earth’s
mantle (causes volcanic activity and mountain building along the
edge of the upper plate)
•
Continental shelves: areas of the seafloor that slope gently away
from the coastlines of most continents
•
Continental slopes: drop away from the outer edges of continental
shelves to the great depths of the ocean; level off into the deep
ocean floor
Cool Fact
• Along the ocean floor, there are ridges and valleys
• Seamounts are tall underwater mountains. Most
were formed by volcanoes
• When the top of a seamount rises above the water’s
surface, an island is forms.
• The Hawaiian Islands are the tops of a chain of
volcanic seamounts.
Check for Understanding
• The theory that Earth’s crust is broken up into large
pieces that move and interact is called
•
•
•
•
(a) evolution
(b) mountain building
(c) the rock cycle
(d) plate tectonics
Rock Dating
• Relative Age: the age of an object in relation to the
ages of other objects
• Law of superposition: an un-deformed sedimentary
rock layer is older than the layers above it and
younger than the rock layers below it
• Absolute Dating: numeric age
Absolute Dating
• Rates of erosion or depositions
• Varve count: definite annual sedimentary deposits
• Radiometric dating: method of using radioactive decay to
measure absolute age
• Half-life: the time it takes half the mass of a given amount of
a radioactive isotope to decay into its daughter isotope
• Carbon dating
• Fossil record