2. What makes an object hot?
Movement of
particles
Heat moves toward
colder areas
3. 3 Types of Heat Transfer
Radiation
Conduction
Convection
4. Radiation
Transfer of energy through space
No direct contact between heat
source and an object.
Can you think of examples of
Radiation?
• Sunlight warming us during the day
• Being warmed by a fire
5. Conduction
Heat transfer within
a material, or
between materials
that are touching.
The particles heat
up, move faster,
and bump into
other particles that
do the same.
6. Conduction: Examples
A spoon sitting in a
boiling pot of soup.
Hot sand at the
beach.
Cold hands after
making a snow
ball.
7. Convection
Heat is transferred by the movement
of fluids and gases.
Heated particles begin to flow, and
transfer heat from one particle to
another.
This is caused by differences in
temperature and density* in a fluid.
• Density = a measure of how much mass
there is in a substance. Example: Rock
is much denser than water.
8. Convection Currents
How does hot liquid move?
Think of the boiling pot of soup:
• The soup on the very bottom of the pot
is the hottest, and therefore, less dense.
It begins to float towards the top.
• Once at the top, it cools, which
increases its density. It becomes
heavier, and due to gravity, falls back to
the bottom of the pot.
9. Convection currents take on a circular
motion.
This is how the mantle rock moves inside
the earth.
10. Changes in Density
The heating and cooling of a fluid changes
its density.
• What a fluid is heated, it’s particles move
farther apart at a faster speed than when it
was cold. As the particles spread out they
take up more space.
• The particles of the fluid are now being
stretched over a larger area, and therefore,
the density of the fluid decreases.
11. Inside the Earth
Heating and cooling of a fluid,
changes in the fluid’s density, and
the force of gravity combine to set
convection currents in motion.
Heat from the core and mantle
causes these types of convection
currents in the mantle.
12. The flowing mantle
Plumes of mantle rock rise slowly
from the bottom of the mantle
toward the top.
The hot rock eventually cools, and
sinks back through the mantle.
This cycle of rising and sinking is
repeated over and over.
This has been happening inside our
earth for more than 4 billion years!
13. Convection Currents in Action:
http://duedall.fit.edu/wholeearth/PH
ysical%20geology%20animations/00
53.swf
