Section 17.4 Convection Currents

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Transcript Section 17.4 Convection Currents

1. What are the three types of plate
2. Describe the direction of movement of
these boundaries.
Chapter 17
Plate Tectonics
Section 17.4
Convection Currents and the
• 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
• Heat Transfer:
– The movement of energy from a warmer object to a
cooler object.
• Radiation:
– 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.
• List the three types of heat transfer.
– Radiation
– 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.
• 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.
• 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
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.
• 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
– 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