Transcript Energy in Earth`s Processes

ENERGY IN
EARTH’S PROCESSES
UNIT FIVE
Energy from the Sun
•Energy is the ability to do
work.
•Everything that happens in
the universe involves work in
some fashion.
•We can think of the earth
like a machine that is
“driven” by two “heat
engines” one that is internal
and one that is external.
•The external heat engine
drives most of our surface
process and is powered
mainly by energy from the
sun.
•Heat from the core of the
earth and the resultant
mechanical energy is the
internal source of Earth’s
energy.
•Electromagnetic energy is a
type of energy that is
radiated in the form of
transverse waves from all
matter not at absolute zero.
This is the type of energy
radiated by the sun; in fact,
by all stars.
•A wavelength is the
distance from the crest of
one wave to another. It
can also be described as
the distance between any
two corresponding points
on a successive cycle.
EmE
•Visible light is the only
wavelength in the
electromagnetic spectrum
that can be seen by the
human eye.
•Infrared energy is often felt
due to its heating effects.
•Ultraviolet radiation tans or
burns the skin; and can
cause cancers, blindness
and/or tissue mutations with
prolonged exposure.
EmE and the Atmosphere
•When EmE comes into contact
with a material, the waves of
energy interact with that
material.
•Depending upon the material
and the angle of interaction, a
number of possibilities can
occur.
Refraction
•or bent…causing the
direction of the waves to
change.
Reflection
•or bouncing off of the
material…causing the
energy to return in the
direction from which it
came.
Scattered
•sent in all directions…this is a
combination of all the
interactions mentioned.
Transmission
•or passing through the
material…continuing on in
the same direction
unchanged.
Absorption
•or taken into….energy is
taken into a material and is
sometimes transformed and
reradiated at a longer
wavelength.
Absorption and Earth’s Surface
•The type of surface
influences how much of the
EmE from the sun is
absorbed.
•The darker the color of the
surface, the more visible
light it will absorb.
•The rougher a surface is, the
more energy it will absorb
and the less it will reflect.
•Mirrors are shiny because
they are smooth and reflect
most of the incoming visible
light.
•The more effective a
material is at absorbing
energy, the better it is at
radiating (or giving off) the
energy.
•A dark colored object will
heat up quickly in sunlight
and cool down quickly after
sunset.
** A good absorber is a good
radiator and heats up and
cools down quickly.
** A poor absorber is a poor
radiator and heats up and
cools down slowly.
Transfer of Energy
•Energy moves from a region
of high concentration (the
source) to a region of low
concentration (the sink).
•Energy will continue to
move from high to low until
the energies are equal,
establishing a state of
dynamic equilibrium.
Methods of transfer
•The transfer of heat energy
from atom to atom or
molecule to molecule when
atoms/molecules vibrate or
collide is conduction.
•Conduction is most
effective in solids –
especially metals – because
the atoms are closer
together than in gases and
liquids.
•The transfer of heat energy
by movement in fluids –
gases and liquids – caused
by the differences in density
within the fluid is
convection.
•Warmer portions have lower
densities and tend to rise
above the cooler portions.
•The higher density portions
are pulled down and
displace the less dense
portions, pushing them
upward
•The result of this motion is a
convection current which is
a circulatory movement
that transfers heat energy
from one place to another.
•Radiation is the method by
which heat energy is
transferred through
electromagnetic waves. No
medium is needed to
transfer the energy.
•This energy can radiate
from its source across empty
space. This is how the EmE
from the sun travels through
space to Earth and the rest
of our solar system.
Transformation of Energy
•A transformation of energy
is the change of one type of
energy into another type.
•Transformation of energy
often occurs when there is
friction.
•When friction occurs, some
of the kinetic energy is
transformed into heat
energy. At the interface
wherever friction occurs,
heat (and sometimes
sound) is formed
•Mechanical energy can be
defined as the total of the
potential and kinetic energy
of an object or system.
•An object in motion has
kinetic energy. The faster it
moves and the more mass it
has, the greater its kinetic
energy.
•Potential energy is energy
related to position or phase.
It can be thought of as stored
energy. The farther an object
is from the center of the
earth, the greater its potential
to fall and the greater its
potential energy.
•There is a direct relationship
between the amount of
mass and the possible
potential energy….as mass
increases, potential energy
increases as well.
•An example of
wavelength
transformation is when
EmE is absorbed by an
object and reradiated
at a longer
wavelength.
•This type of transformation is
common on the surface of
the earth when shorter
wavelength ultraviolet and
visible radiation from the sun
are absorbed and
reradiated as longer
wavelength infrared
radiation.
Measuring Heat Energy
•Temperature is a measure
of the average kinetic
energy of the particles of
matter. It is not a type of
energy…but a measure of
energy!
•The greater the average
kinetic energy of the
particles, the higher the
temperature.
•The type of energy that is
transferred from hot to cold
objects is heat energy and
is measured in joules (a
metric unit of energy or
work)
•The amount of heat energy
needed to raise the
temperature of one gram of
any substance 1ºC is called
the specific heat of that
substance.
•It can be thought of as the
resistance of a material to
heating up or cooling off.
** See page one of your ESRT
•Liquid water has the highest
specific heat of any naturally
occurring substance.
•Because of this, water
heats up and cools
down slowly!
•Therefore...large bodies
of water have a
moderating effect on
climate!
•The higher the
specific heat the
more slowly the
material changes
temperature!
•The lower the
specific heat,
the more
rapidly the
material
changes
temperature!
Energy and Phase Changes
•An increase or
decrease in the
energy and
temperature of matter
can cause the
material to go from
one phase to another.
•Melting is the change in phase
from a solid to a liquid.
•Solidification (or freezing) is the
change in phase from a liquid
to a solid.
–Solidification that results in an
organized pattern of atoms is
called crystallization.
•Evaporation (or
vaporization) is the change
in phase from a liquid to a
gas (vapor).
•Condensation is the change
in phase from a gas (vapor)
to a liquid
•Sublimation is the
changing of a gas
directly to a solid or
from a solid directly
to a gas.
•When water changes phase
from a solid to a liquid to a
gas, it absorbs heat energy;
molecular movement
speeds up and molecules
spread out.
•When water changes phase
from a gas to a liquid to a
solid, it releases stored heat;
molecular movement slows
down and molecules move
closer together.
•While a material remains in
one of the phases of matter,
its temperature increases as
heat energy is added.
•If the material is in
the process of
changing phase,
its temperature
remains the same
as it is heated.
•During the phase change,
the added heat energy is
not increasing the kinetic
energy the temperature is
not increasing.
•The added heat
energy is being
converted to a type
of potential energy
called latent heat.
Earth’s Energy
•The sun radiates energy in a
variety of wavelengths
among which are ultraviolet
rays, visible light and
infrared rays. Visible light is
received at the greatest
intensity.
•Nuclear fusion
generates
energy within
the sun and
provides us with
our external
heat source
•Heat energy from the
Earth’s core is converted
into mechanical energy for
geological processes such
as mountain building, plate
movements and volcanic
eruptions.
•It is believed that
most of the Earth’s
interior energy
comes from the
nuclear decay of
radioactive
materials in Earth’s
core
•Nuclear fission is the
process by which
unstable or radioactive
atomic nuclei split to
form lighter elements.
•In the process, large
amounts of energy are
released.
•Another source of
Earth’s energy is the
energy created by the
impact of meteoroids,
asteroids and comets
with Earth’s
atmosphere and
surface
•There are many other
minor sources of energy
including the
gravitational energy of
the Sun and Moon
which creates the tidal
energy of the oceans as
well as many sources of
friction.