#### Transcript Section 17.4 Convection Currents

```Warm-Up
1. What are the three types of plate
boundaries?
2. Describe the direction of movement of
these boundaries.
Chapter 17
Plate Tectonics
Section 17.4
Convection Currents and the
Mantle
Vocabulary
• Convection Current:
– The movement of a fluid, caused by differences in
temperature, that transfers heat from one part of the
fluid to another.
• Density:
– The amount of mass in a given space; mass per unit
volume.
• Heat Transfer:
– The movement of energy from a warmer object to a
cooler object.
Vocabulary
– The transfer of energy through empty space.
• Conduction:
– The transfer of heat by direct contact of
particles of matter.
• Convection:
– The transfer of heat by movements of a
heated fluid.
Introduction
• List the three types of heat transfer.
– Conduction
– Convection
• What are two forms of radiation?
– Forms of radiation include the heat you
feel from sunlight and the heat you feel
around a flame or open fire.
Conduction
• What is an example of conduction?
– An example of conduction is a spoon
heating up in a pot of hot soup or the skin
of your hand heating up when you touch a
hot spoon.
Convection
• Heat transfer by convection is caused by
temperature and density
differences of ____________
within a fluid.
• A measure of how much mass there is in a
density
volume of a substance is ____________.
• If a pot of soup is no longer heated, when will
the convection currents stop flowing?
– The convection currents will stop flowing when all the
soup has reached the same temperature.
Convection
• Circle the letter of the sentence that
describes what happens to a fluid when its
temperature increases.
– A. Its particles occupy less space
– B. Its density decreases.
– C. Its particles move more slowly.
– D. Its particles settle together more closely.
Convection in Earth’s Mantle
• True or False: Convection currents flow in
the asthenosphere.
– True
• True or False: The heat source for the
convection currents in the mantle is the
sun.
– False
Convection in Earth’s Mantle
• How is mantle convection related to the
movements of tectonic plates?
– The process associated with convection
currents in the mantle that occurs when
the weight of an elevated ridge pushes an
oceanic plate toward a subduction zone is
called ridge push
– Another process that occurs as the weight
of the subducting plate pulls the trailing
lithosphere into a subduction zone is
called slab pull
Convection in Earth’s Mantle
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