Transcript Chapter 2 Earth as a System

Chapter 2 Earth as a System
Section 1 Earth: a Unique Planet
Prove to me that the Earth is Round!
Proof
• We do not see the
bottom of a boat
when it sails away
• We can see pictures
from space
Lunar Eclipses
Eratosthenes Greek astronomer from ~ 2000 years ago determined the circumference of the
round earth. He used two wells, the angle of the sun's shadow and the
distance between the two wells to determine the circumference.
Eratosthenes was within 15% of the correct answer. He made two mistakes
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The wells were not dug straight down
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Seine and Alexandria are not directly north and south of each other.
Earth Basics
• The earth is 3rd rock from the sun. She was formed over 4.6
billion years ago. Approximately 71% is covered in water, hence
the nickname "The Blue Planet".
• It is not a true sphere. We are called an OBLATE SPHEROID or
better yet, SPHEROIDAL. We have two different measurements
for the circumferences.
• Earth's Circumference:
Equatorial 40,074 kms
Polar 40,007 kms.
• Earth's Diameter:
Equator
12,756 kms (7,972.5 miles)
Poles
12,714 kms (7,946.25 miles)
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3% difference
Earth's Interior
The Layers of the Earth: Science Reference Tables :OSA:NYSED
Crust - Lithosphere
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1% of Earth's mass
The thickness and depth varies
under oceans 5 to 10 km
under continents 15 to 80 km
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All drilling and mining is done in this layer - we have never gone
crust.
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Made up of lighter rocks and minerals.
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Temperature increases with depth until it reaches approx 1000o C
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Below 70 meters the temperature starts to increase 1o C for every 40 meters of
depth. The rate slows down after several kilometers so that the center of the earth is
approximately 6000 – 7000o C.
deeper than the
AsthenosphereThis is the thin slush like layer between the crust and mantle
Moho (Mohorovici discontinuity)
Mantle • Approximately 2/3 mass of the Earth's mass
• Approximately 2900 km thick
• The temp is between 1500 – 3200 o C
• The temp increases with depth
• It is a solid with liquid properties
• It is made up of heavy metals:
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Iron (Fe)
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Magnesium (Mg)
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Silicon (Si)
Outer Core •
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The depth is approximately 3000 – 5000 km
The temp is between 5000 – 6000o C
The temp increases with depth
It is made up of liquid like metals:
Iron (Fe)
Nickel (Ni)
Inner Core •
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The depth is approx 5000 – 6000 km
The temp is approx 6500o C p
It is made up of solid:
Iron (Fe)
Nickel (Ni)
Why does the temperature
increase in the crust?
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Compression
Radioactive decay – Uranium and
Potassium gives off heat energy with the
crust.
There may be still some heat left over
from the earth’s formation.
Friction from movement of and in the
crust.
Earth as a magnet:
• The magnetic field in the Earth is like having a bar
magnetic inside a ball. The positive end is the north (we
use a compass to prove this) and the negative end is the
South Pole.
• True North which is where North and South Pole are,
magnetic north is about 11o different. This becomes
evident when you look on maps; you will see two arrows
to point to either magnetic north or true north.
• Our magnetic field helps protect us against the harmful
solar winds produced by the sun.
Earth's Gravity:
• Weight is the measure of the strength of the pull
of gravity on an object. Measured in Newton.
Can change depending on where you are.
• Mass is how much stuff is in side of an object. It
depends on volume. Does not change
depending where you are.
• Where do we weigh more? At the North Pole or
the Equator
Why?
The North Pole – because you are closer to the middle of the
earth and gravity has more pull on you. Gravity is the force that
holds us together and holds us on the earth. As the earth spins,
the gravity pulls us closer to the center of the earth, which is the
center of gravity. The difference is about 0.3% less!
Section 2 Energy in the Earth
System
• Systems:
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A group of objects that interact with
each other to create something whole.
The system may seem to work alone,
however, most systems are linked to one
another. Uses Matter and Energy
• Matter - anything that has mass and takes
up space.
• Energy - the ability to do work. Can be
heat, light, vibrations, even
electromagnetic waves.
There are two types of systems (ok maybe a third that I made up).
Open – an Island
An open system is a state of a system, in which a system continuously
interacts with its environment. A free transfer of energy or matter.
Closed – a biodome
A closed system is a system in the state of being isolated from the
environment. It is often used to refer to a theoretical scenario where perfect
closure is an assumption, however in practice no system can be completely
closed; there are only varying degrees of closure. A limited exchange of energy
and matter.
Quasi - Earth.
The exchange or transfer of energy or matter is limited.
Earth's Four Spheres
Using these systems we can learn a great deal. There
are 4 main systems (spheres) that we study.
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Atmosphere- the air surrounding the earth
Hydrosphere- all waters: ocean, rivers, lakes and groundwater
Geosphere – hard surfaces including volcanoes and such
Biosphere – all living things great and small
• http://www.classzone.com/books/earth_science/terc/content/vis
ualizations/es0102/es0102page01.cfm?chapter_no=visualizatio
n
Our interactions between all of the “spheres” make us very
DYNAMIC. Some of the interactions are small and minor, some
are quick and massive while others cover such a large scale
that they take so long we don’t notice.
Dynamic – what is it??????
It means ever changing and interacting. Sometimes
interactions occur on a one time basis, and some occur
on a regular basis. We call these “cycles” or “cyclic”.
The ones that make us dynamic are water, carbon,
nitrogen and phosphorus and energy.
Even though we are Dynamic, we are also balanced –
matter can neither be created nor destroyed so we
maintain a balance called DYNAMIC EQUALIBRIUM.
This simply means that for every action, there is an
equal reaction. For every mountain that erodes, one is
created by volcano. For every rain drop that falls, more
is evaporated. And so on.
Earth's Energy Budget
• Energy exists in many forms, such as heat, light, chemical energy, and
electrical energy. Energy is the ability to bring about change or to do work.
Thermodynamics is the study of energy.
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Two types of Energy
Internal Source:
Geothermal - from inside the earth
Compression
Radioactive decay – Uranium and Potassium gives off heat energy with the
crust.
• There may be still some heat left over from the earth’s formation.
• Friction from movement of and in the crust.
• External Source:
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This is really not like a cycle at all but a budget or a balance sheet. The
amount of energy coming into a system should always equal the amount of
energy going out. That is why it is also called the Earth’s Energy Budget.
External Source:
This is really not like a cycle at all but a budget or a balance
sheet. The amount of energy coming into a system should always
equal the amount of energy going out. That is why it is also called the
Earth’s Energy Budget.
Some of the energy is directly used like the solar, tidal and geothermal. And some is
stored for later usage like fossil fuels, water, ice, live plants and some sedimentary
rocks.
Unlike the other cycles – a little energy is lost and
never retrieved. This is called the physics of the Law
of Thermodynamics.
Law I
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Energy can never be created nor destroyed, only changed from one form to
another.
Law II
When energy changes, it is converted from a more organized, more
concentrated form to a less organized, less concentrated one (some energy
is always lost making it so).
Potential energy, as the name implies, is energy that has not yet been used,
thus the term potential. Kinetic energy is energy in use (or motion). A tank of
gasoline has a certain potential energy that is converted into kinetic energy
by the engine. When the potential is used up, you're outta gas!
Humans and insects and other live creatures also have an effect the
interactions of the cycles and systems that occur on Earth. It causes the
ripple effect. When someone does something in one area, it triggers a
chain reaction elsewhere. Like the butterfly that flaps its wings in Africa that
produces a Hurricane on Long Island.
The Cycles In the Earth:
Nitrogen Cycle
Nitrogen is a gas. Our atmosphere is approximately 78%
nitrogen. We cannot use this for life. In order to use it, it must go
though some changes,
called fixing. It means it changes it from
the air version to the compounds we can use though a chemical
process.
Air to soil through nitrogen fixing
Soil to plant and animal (plants use it to grow - animal eats plants)
Back to air though decay
Repeat
Carbon Cycle
Carbon is never destroyed – just rearranged from one form to another. Sometimes it is a quick change like
a decomposing apple and then it sometimes takes a very long time like a plant decaying, being buried and
squished then later burned as coal.
• Even though we feel that carbon can be dangerous
(carbon monoxide, etc), it is essential for life. It is the
building block for all organic materials and organism.
We are carbon based life forms, just ask any alien.
• Carbon enters the atmosphere as a by-product (bad
breath, fluctuant, composts, volcanoes, etc.)
• Carbon is removed from the atmosphere by:
– Plants for photosynthesis
– Phytoplankton uses it for photosynthesis and when they die
they release it into the water that releases it.
• Carbon is diffused out of the oceans (diffuse means to
move from high concentrations to low and since the air
is lower than the water it is released into the air)
Phosphorus cycle
• Phosphorus moves through every sphere except the atmosphere because it
is rarely a gas.
• It gets to the soil from rocks breaking down and being dissolved in water, or
when an animal dies.
• Plants absorb it and it becomes part of them
• Animals eat the plant, and both die, returning it to the ground.
Water Cycle
• 97% of water is in oceans - salt water
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2 ½ % of water is frozen - glaciers
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½ % of water is fresh drinking
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streams - very little
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rivers – very little
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lakes – a little more
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swamps – a little more
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UNDERGROUND- majority of drinking water
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Water Cycle Terms
Evaporation - water vapor going into the atmosphere
- usually by the sun, directly or indirectly
Condensation - water gas (H2Og) changing to Water Liquid (H2Ol)
- must have condensation nuclei (dust) to form clouds
Precipitation - gravity pulling water from the clouds- moisture source
for local water budget.
Transpiration - process by which green plants lose water through their
leaves
evapotranspiration - evaporation & transpiration combined
the way most water enters the air
Section 3 - Ecology
• Ecosystem
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A community of organism and the abiotic (non living) environment
they inhabit.
• Balancing the forces in an Ecosystem
• Small changes in any part of the environment can affect the ecosystem,
however, the system usually has the ability to maintain and restore itself.
• When the change is a large one, like a fire or a flood, the ecosystem can
be disrupted for some time. Eventually it will go back to its normal state.
• Energy Transfers in an Ecosystem
• The sun is the ultimate source of energy. The energy is cycled through the
various cycles and it all works together.
• Humans as stewards of the Environment
• All Earth's systems are interconnected. A change in one system can effect
another system.
• By helping preserve the environment and not treating Mother Earth poorly
we become stewards of the planet. We become responsible for Mother
Earth and her wellbeing. In other words, don't hurt Mother Nature.
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