Transcript Earth as a System

Earth as a System
Chapter 2
• Earth Facts:
– the third planet from the sun in our solar
system
– formed about 4.6 billion years ago
– made mostly of rock.
– Approximately 70% of Earth’s surface is
covered by a
– Earth is an oblate sphere
– Pole-to-pole circumference is 40,007 km.
– Equatorial circumference is 40,074 km.
– Average diameter is 12,756 km.
• Seismic waves – waves that travel
through Earth; they are caused by
earthquakes and by explosions near
Earth’s surface.
• Important discoveries have been
made about Earth’s interior through
studies of seismic waves
3 Major Compositional Zone:
– Crust
– Mantle
– Core
5 Major Structural Zones:
–
–
–
–
–
Lithosphere
Asthenosphere
Mesosphere
Liquid Outer Core
Solid Inner Core
Layers of Earth
Compositional Zones of Earth’s Interior
• Crust - thin and solid outermost layer, lies above
the mantle
• Oceanic crust - lies under the oceans, is only 5 to
10 km thick. (3-5 mi)
• Continental crust varies in thickness from 15 km
to 80 km. (avg 25 mi)
• Mantle - layer of rock that lies between Earth’s
crust and core
– is nearly 2,900 km thick and makes up almost twothirds of earth
• Core - the central part of Earth that lies below
the mantle
– a sphere composed mainly of nickel and iron whose
radius is about 3,500 km
• The crust is composed of two types of rock.
– The continental crust is mostly granite.
– The oceanic crust is basalt. Basalt is much
denser than the granite.
• Because of this the less dense continents
ride on the denser oceanic plates.
Structural Zones of Earth’s Interior
• Lithosphere - solid, outer layer of Earth
that consists of the crust and the rigid
upper part of the mantle
– between 15km and 300 km thick.
• Asthenosphere - solid layer of the mantle
beneath the lithosphere; made of mantle
rock that flows very slowly, which allows
tectonic plates to move on top of it
– about 200 km thick
Convection Currents
• The middle mantle
"flows" because of
convection currents.
Convection currents
are caused by the
very hot material at
the deepest part of
the mantle rising,
then cooling and
sinking again -repeating this cycle
over and over.
Convection Currents
The next time you heat anything
like soup or water in a pan you
can watch the convection
currents move in the liquid.
When the convection currents
flow in the asthenosphere they
also move the crust. The crust
gets a free ride with these
currents, like the cork in this
illustration.
Safety Caution: Don’t get your
face too close to the boiling
water!
• Mesosphere - strong, lower part of the
mantle between the asthenosphere and
the outer core
– reaches from the bottom of the
asthenosphere to a depth of about 2,900 km.
• Liquid outer core -below the mesosphere
surrounds the solid inner core
• Solid inner core - begins at a depth of
5,150 km, composed of nickel and iron
Outer Core
• The core of the Earth
is like a ball of very
hot metals. The
outer core is so hot
that the metals in it
are all in the liquid
state. The outer core
is composed of the
melted metals of
nickel and iron.
Earth’s
Interior
Core
• The inner core of the Earth has
temperatures and pressures so great
that the metals are squeezed together
and are not able to move about like a
liquid, but are forced to vibrate in
place like a solid.
Layers of Earth
Earth as a Magnet
• Magnetosphere - extends beyond the
atmosphere
• Where the magnetic field balances the
pressure of the solar wind – 63,000 km
• Scientists think that motions within the
liquid iron of Earth’s outer core produce
electric currents that in turn create
Earth’s magnetic field.
Magnetosphere
Earth’s Gravity
• Gravity - the force of attraction that exists
between all matter in the universe
• Newton’s law of gravitation - the force of
attraction between any two objects
depends on the masses of the objects and
the distance between the objects
• The larger the masses of two objects are
and the closer together the objects are, the
greater the force of gravity between the
objects will be.
• Weight - measure of the strength of the pull of
gravity on an object
• An object’s weight depends on its mass and its
distance from Earth’s center
Weight and Location
• Because the distance between Earth’s surface
and its center is greater at the equator than at
the poles, the weight of an object at the
equator is about 0.3% less than its weight at the
North Pole
• Matter - anything that has mass and takes up
space.
• Energy - the ability to do work. Energy can be
transferred in a variety of forms, including heat,
light, vibrations, or electromagnetic waves.
Closed Systems
• system in which energy, but not matter is
exchanged with the surroundings.
Open Systems
• system in which both energy and matter are
exchanged with the surroundings
The Earth system is almost a closed system because matter
exchange is limited
Energy enters the system in the form of sunlight and is released
into space as heat.
Only a small amount of dust and rock enters, and only a fraction
of the hydrogen atoms in the atmosphere escape into space.
4 Spheres of Earth:
• Atmosphere
• Hydrosphere
• Geosphere
• Biosphere
• Atmosphere - mixture of gases that
surrounds a planet or moon
– The atmosphere provides the air you
breathe and shields Earth from the sun’s
harmful radiation
• Hydrosphere - portion of Earth that is
water
– Water covers 71% of Earth’s surface.
– occur in the form of oceans, lakes, rivers,
streams, glaciers and ice sheets, and
groundwater.
• Geosphere - the mostly solid, rocky part of
Earth; extends from the center of the core
to the surface of the crust
– all of the rock and soil on the surface of the
continents and on the ocean floor.
– also includes the solid and molten interior of
Earth.
• Biosphere - part of Earth where life exists;
includes all of the living organisms
– composed of all of the forms of life in the
geosphere, in the hydrosphere, and in the
atmosphere, as well as any organic matter that
has not decomposed.
– The biosphere extends from the deepest parts
of the ocean to the atmosphere a few
kilometers above Earth’s surface.
Earth’s Energy Budget
• Ecology - the study of the relationships
between living things and their nonliving,
or abiotic environment.
• Ecosystem - a community of organisms and
their abiotic environment
– An ecosystem may be as large as an ocean or as
small as a rotting log. The largest ecosystem is
the entire biosphere.
• Producers - organisms that make their own
food, most producers use energy from the
sun to produce their own food
• Consumers -organisms that get their energy
by eating other organisms.
• Decomposers – a consumer that get energy
by breaking down dead organisms
• To remain healthy, an ecosystem needs to
have a balance of producers, consumers,
and decomposers
Concentration of Plant Life on Earth