Download Chapter 2-Earth as a System

Section 1 – Earth: A Unique
Planet
Section 2 – Energy in the Earth
System
Section 3 - Ecology
Earth is the only known planet in the solar system
that has liquid water on its surface and atmosphere
that contains a large proportion of oxygen.
 Earth is the only known planet to support life.
 Earth is mostly made of rock.
 Approximately 71% of the Earth’s surface is covered
by a thin layer of water called the global ocean.
 Earth appears to be a perfect sphere, but it is
actually an oblate spheroid, or slightly flattened
sphere. The spinning Earth flattens at the poles and
bulges in the equatorial zone.
 The Earth’s surface is relatively smooth.

 Direct
observation of the Earth’s interior
is limited to the upper few kilometers
that can be reached by drilling.
 Scientists use seismic waves as an
indirect method to study the Earth at
greater depths. Seismic waves are
vibrations that travel through the earth.
After studying these waves, scientists
have determined that the Earth is made
up of three major compositional zones
and five major structural zones.
 The
three compositional zones:
• The crust – the thin, solid, outermost zone of
earth. The crust beneath the oceans is called the
oceanic crust. The crust beneath the continents
is called the continental crust. continental crust
is thickened beneath high mountain ranges.
• The mantle – the denser layer that underlies the
crust. It is 2,900 km thick and makes up 2/3 of
the Earth’s mass.
• The core – the center sphere composed mostly
of iron and nickel.
 The
mantle is divided into 3 zones:
• The uppermost part is cool and brittle. This part
and the crust above it is called the lithosphere.
• Below the lithosphere is a layer under great
pressure and heat. This solid rock has the ability
to flow (called plasticity). This layer is the
asthenosphere.
• Below the asthenosphere is a layer of solid
mantle rock called the mesosphere.
• The Core is divided into two sections:
• The inner core is a dense, rigid solid.
• The outer core is a dense liquid.
 The
Earth is a magnet. It has two
magnetic poles. The lines of force of the
Earth’s magnetic field extends beyond
the atmosphere and affects a region of
space called the magnetosphere.
 The source of the Earth’s magnetic field
may be the liquid iron core.
 There is some question about where it
comes from now because both the sun
and the moon also have magnetic fields.
 Gravity
is the force of attraction that exists
between all matter in the universe.
 According to the law of gravitation, the force
of attraction between two objects depends
on the masses of the objects and the
distance between the objects.
 Weight is a measure of the strength of the
pull of gravity on an object. The weight of
an object depends on its mass and its
distance from Earth’s center.
 Why would your weight be 0.3% less at the
equator than at the North Pole.
A system is an organized group of related
objects or components that interact to create a
whole.
 A closed system is a system in which energy, but
not matter, is exchanged with the surroundings.
A closed system is sealed.
 An open system is a system in which both energy
and matter is exchanged with the surroundings.
A lake is also an open system.
 All systems that make up the Earth system are
open, but the Earth system is almost a closed
system because matter exchange is limited.

 The
Earth’s system is composed of four
“spheres” that are storehouses of all the
planet’s matter.
• The Atmosphere – the blanket of gases that
surrounds the Earth’s surface. 78% Nitrogen, 21%
oxygen, 1% other gases
• The Hydrosphere – all the Earth’s water except the
water that is in gaseous form in the atmosphere
• The Geosphere – the mostly solid part of the Earth.
It includes both solid and molten interior
• The Biosphere – composed of all of the forms of life
in the geosphere, the hydrosphere and the
atmosphere.
Transfers of energy between Earth’s spheres can be
thought of as parts of the energy budget, in which
additions in energy are balanced by subtractions.
 First Law of Thermodynamics – energy is transferred
between systems, but it cannot be created or
destroyed.
 Second Law of Thermodynamics – when energy
transfer takes place, matter becomes less organized
with time.
 Matter and energy are constantly being exchanged
between spheres. This constant exchange happens
through chemical reactions, radioactive decay, the
radiation of energy (including heat and light), and
the growth and decay of organisms.

 Internal
sources of energy come from the
radioactive decay of atoms in the center
of the earth.
 The most important external source of
energy in the system is the sun. Another
source of external energy is the
gravitational energy from the sun and the
moon.
A
reservoir is a place where matter or
energy is stored.
 A cycle is a group of processes in which
matter and energy repeatedly move
through a series of reservoirs.
 These cycles rely on energy sources to
drive them.
 The length of time that energy or matter
spends in a reservoir can vary from a few
hours to several million years.
 The Nitrogen Cycle
• Moves nitrogen from the air to soil, from soil to plants,
and animals and back to air again.
• Bacteria take the nitrogen from the air and fix it into the
soil.
 The Carbon Cycle
• Plants convert carbon dioxide from the atmosphere into
carbohydrates. Organisms eat the carbohydrates and
release carbon dioxide back into the air.
 The Phosphorus Cycle
• Phosphorus enters soil and water when rock breaks
down. Plants absorb the phosphorus through roots and
incorporate into tissues. Animals eat plants. When plants
or animals die, the phosphorus returns to the
environment through decomposition.
• The Water Cycle – the movement of water from the
atmosphere to the Earth and back to the atmosphere
through the processes of condensation, precipitation and
evaporation.
Ecology is the study of the complex relationships
between living things and their nonliving
environment.
 Ecosystem – a community of organisms and the
environment that the organisms inhabit. Each
ecosystem on Earth is a distinct, self-supporting
system.
 Organisms that make their own food are called
producers. Producers are a source of food for
other organisms.
 Consumers are organisms that get their energy
by eating other organisms.
 Some consumers get energy by breaking down
dead organisms. These consumers are called
decomposers.

 Carrying
capacity – the largest population
that an environment can support at any
given time
 Changes in any one part of an ecosystem
may affect the entire system in
unpredictable ways.
 Food Chain – the sequence in which
organisms consume other organisms
 Food Web – used to represent the
relationships between multiple food chains
 Pollution – the contamination of the
environment with harmful waste products or
impurities.