Transcript Chapter 3 Section 3 Science PowerPoint

The Cycling of Energy
Key Concept: Various Heat-exchange
systems work in the Earth’s system and
affect phenomena on Earth’s surface.
What You Will Learn
• Heat flow is the transfer
of energy from a
warmer object to a
cooler object.
• Energy from the sun,
the major source of
energy for phenomena
on Earth’s surface, is
transmitted to Earth by
radiation.
• Heat from Earth’s
interior reaches the
surface mostly by
convection.
The Flow of Energy
• Energy can be carried
from one place to another
by heat flow, waves, or by
moving objects.
• Heat flow is the transfer
of energy from a warmer
object to a cooler object.
• Waves—such as water
wave, light waves, and
sound waves—transfer
energy through
vibrations.
• Waves move energy, but
they do not move matter.
• Objects carry energy
while they are moving.
• As they move, the objects
pass energy to objects
that they touch.
• The sun is the major
source of energy for the
Earth system.
• Heat from Earth’s interior
supplies a much smaller
amount of energy.
• Energy moves through
the processes of
radiation, convection, and
conduction.
Radiation
• All energy from the sun travels to Earth in waves called
electromagnetic radiation.
• Electromagnetic radiation contains a wide range of
wavelengths, collectively referred to as the
electromagnetic spectrum.
• Radio waves have the longest wavelengths, gamma rays
have the shortest wavelengths.
• All energy that Earth receives from the sun travels
through space as electromagnetic radiation.
• Wavelengths in or close to the visible light range make
up most of the energy given off by the sun.
• Some of this energy can pass through Earth’s
atmosphere and reach Earth’s surface.
• Energy from the sun
drives the water cycle
and makes life possible
on Earth.
• Energy from the sun is
absorbed by Earth’s
systems.
• This energy is then
converted to thermal
energy and transferred
by convection and
conduction.
Convection
• Most energy is moved
through Earth’s systems
by convection.
• Most convection occurs in
fluids, such as water and
air.
• Some convection can
occur in solids that flow
like putty.
• The uneven heating of
matter drives convection.
• Matter that is heated
becomes less dense and
rises. Cooler, denser
matter sinks.
• The movement of matter
that results from
difference in density is
called a convection
current.
• In the ocean, differences in temperature and
salinity cause differences in density.
• Salinity is the amount of salt in salt water.
• Cold, salty water has a higher density than warm,
less-salty water.
• In the ocean, convection causes deep currents.
• Deep currents are stream like movements of water
far below the ocean surface.
• Deep currents take more than a thousand years to
travel around the entire ocean.
• Convection
currents in the
atmosphere form
when cold air sinks
and forces warm
air away from
Earth’s surface.
Convection in the Geosphere
• Convection also occurs
in the geosphere.
• Energy produced deep
inside Earth heats rock
in the mantle.
• The heated rock is
under high pressure, so
it becomes plastic
without melting.
• The heated rock flows like putty.
• As it becomes less dense, the heated rock rises
toward Earth’s surface.
• The cooler, denser rock surrounding the heated rock
sinks.
• In this way, heat inside
Earth moves toward the
cooler crust.
• This movement of rock
is a convection current.
• Convection currents in
the mantle cause the
movement of tectonic
plates.
Conduction
• When objects at
different temperatures
touch, their particles
interact with each other.
• Fast-moving particles in
the warmer object
transfer energy to
slower moving particles
in the cooler substance.
• This causes the
particles in the cooler
substance to move
faster and get warmer.
• Energy can be transferred between the geosphere and the
atmosphere by conduction.
• When Earth’s surface is warmer than the atmosphere, the
ground will transfer energy to the atmosphere.
• When air comes into direct contact with the Earth, that
energy is transferred by conduction.
Earth’s Energy Budget
• Energy on Earth moves
through and between
four spheres.
• These four spheres are
open systems, which
means they constantly
exchange energy with
each other.
• Energy is neither
created nor destroyed.
• It is simply transferred between spheres
and converted into another form of energy.
• You can think of this movement of energy
as part of an energy budget.
• An addition of energy in one sphere
means a subtraction of energy in another.