The Earth’s Internal Heat
Objectives
1. Describe where the Earth’s internal heat
comes from.
2. Identify the sources of Earth’s internal heat;
namely, radiogenic heat and primordial heat.
3. Describe the parts and function of Earth’s
interior.
4. Describe the processes of heat transfer in
Earth’s mantle.
Heat energy plays a vital role in
our planet. It is one of the
extreme factors in what makes
the world livable.
The heat inside of our planet moves
continents, build mountains and causes
earthquakes.
Sources of heat in our planet
can be identified as:
a)Primordial heat
b)Radiogenic heat
Primordial heat
•the internal heat energy that gradually
gathered together by means of
dispersion in the planet during its few
million years of evolution
•Heat gathered during the early
formation of the Earth
The major contribution of this
internal heat is the accretional energy
– the energy deposited during the
early formation of a planet.
•The core is a storage of primordial heat
that originates from times of accretion
when kinetic energy of colliding
particles was transformed into thermal
energy. This heat is constantly lost to
the outer silicate layers of the mantle
and crust of the earth through
convection and conduction.
•In addition, the heat of the core
takes tens of thousands of years to
reach the surface of the earth.
Today, the surface of the earth is
made of a cold rigid rock since 4.5
billion years ago, the earth’s surface
cools from the outside but the core is
still made of extremely hot material.
Radiogenic Heat
•the thermal energy released as a result
of spontaneous nuclear disintegration
•It involves the disintegration of
natural radioactive elements inside the
earth – like Uranium, Thorium and
Potassium.
•Uranium is a special kind of
element because when it decays,
heat (radiogenic) is produced.
Radioactive elements exist
everywhere on the earth in a fairly
significant concentration. Without the
process of radioactive decay, there
would be fewer volcanoes and
earthquakes – and less formation of
earth’s vast mountain ranges.
•Estimated at 47 terawatts (TW), the
flow of heat from Earth's interior to the
surface and it comes from two main
sources in equal amounts: the
radiogenic heat produced by the
radioactive decay of isotopes in the
mantle and crust, and the primordial
heat left over from the formation of the
Earth.
Name the
Layers!!!
1
2
1. Crust
3
2. Mantle
3. Outer Core
4
4. Inner Core
Three Layers of the Earth
•Crust
•Mantle
•Core
The crust
•This is the outside layer of the earth
and is made of solid rock, mostly
basalt and granite. There are two
types of crust; oceanic and
continental.
•Very thin layer
•Oceanic crust is denser and thinner
and mainly composed of basalt.
•Continental crust is less dense,
thicker, and mainly composed of
granite.
The mantle
•The mantle lies below the crust and is
up to 2900 km thick. It consists of hot,
dense, iron and magnesium-rich solid
rock. The crust and the upper part of
the mantle make up the lithosphere,
which is broken into plates, both large
and small.
The core
•The core is the center of the earth
and is made up of two parts: the
liquid outer core and solid inner core.
The outer core is made of nickel, iron
and molten rock. Temperatures here
can reach up to 5,000 C.
0
Which of Which?
Identify the sources of internal heat.
Write RH for Radiogenic heat and PH
for Primordial Heat. Write your answer
on a sheet of paper.
1. Presence of different isotopes of heat producing
element in the mantle and crust.
2. Internal heat accumulated by dissipation of planet.
3. Release of accretional energy.
4. Process involved in mantle convection.
5. Release of thermal energy as a result of
spontaneous nuclear disintegration.
Find Them!!!
•MANTLE •RADIOGENIC
•CONVECTION •TECTONIC
•CURRENT •HEAT
•PRIMODIAL •RADIATION
•EARTH •CONDUCTION
Heat Transfer
•Three processes can transfer heat:
conduction, convection, and radiation.
Conduction
•governs the thermal conditions in
almost entire solid portions of the Earth
and plays a very important role in the
lithosphere.
Conduction
•Technically, it can be defined as the
process by which heat energy is
transmitted through collisions
between neighboring atoms or
molecules.
Convection
•involves transfer of heat by the
movement of mass, which is a more
efficient means of heat transport in
the Earth compared to pure
conduction.
•governs the heat transport in the fluid
outer core and the mantle.
Radiation
•the least important mode of heat
transport in the Earth.
•The process of heat exchange
between the Sun and the Earth,
through radiation, controls the
temperatures at the Earth's surface.
Imagine and Explain
Chocolate candy in your hand will
eventually melt as the heat from your
body is released and makes it melted.
What type of transfer is this? Why?
A heater in the hot air balloon heats the
air. The air inside is trapped causing the
balloon to rise. What transfer is this?
Why?
