Transcript File - Ms. D. Science CGPA

Earth’s Structure and Materials- Course 2
3.2 Convection and the Mantle
Ms. De Los Rios
7th Grade Science
CGPA
Vocabulary 3.2
1. Radiation- The transfer of energy by electromagnetic waves.
2. Convection- The transfer of heat by the movement of a fluid.
3. Conduction- The transfer of heat from one particle of matter
to anther.
4. Convection Current- The movement of fluid, caused by
differences in temp. that transfers heat from one part of the
fluid to another.
5. Density- The ratio of the mass of a substance to its volume
(mass/volume)
My Planet Diary- Lighting Up the Subject pg. 106
Misconception: Rock cannot flow.
Did you know that the solid rock in Earth’s mantle
can flow like a fluid?
To learn how, look at this image of a lava lamp.
Heat from a bulb causes solid globs of wax at the bottom
of the lamp to expand. As they expand, the globs become
less dense. The globs then rise through the more dense
fluid that surrounds them. In Earth’s mantle, great heat
and pressure create regions of rock that are less dense
than the rock around them. Over millions of years, the
less dense rock slowly rises—like the solid globs in the
lava lamp!
My Planet Diary- Lighting Up the Subject pg. 106
Compare and Contrast:
Think about your own observations of liquids that
flow. How is flowing rock different from flowing
water?
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How is Heat Transferred?
Heat is constantly being transferred inside Earth and all
around Earth’s surface.
What is heat transfer????
The movement of energy from a warmer object to a cooler object.
Three types of heat transfer:
radiation, convection, and conduction.
The transfer of energy that is carried in rays like light is called radiation.
Heat transfer by the movement of a fluid is called convection.
Heat transfer between materials that are touching is called conduction.
Radiation
The sun constantly transfers light and heat through the air,
warming your skin. The transfer of energy that is carried in rays
like light is called radiation.
Examples of radiation:
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Conduction
Have you ever walked barefoot over hot sand? Your feet can
feel as if they are burning! That is because the sand transfers its
heat to your skin. Heat transfer between materials that are
touching is called conduction.
Examples of Conduction:
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Convection
Seagulls often soar on warm air currents. The currents are
created as warm air rises from the ground The warm air heats
cooler air above it Heat transfer by the movement of a fluid is
called convection.
Examples of Convection:
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Assess Your Understanding pg. 107
I get it! Now I know that the three types of heat transfer are
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How Does Convection Occur in Earth’s Mantle?
Pg. 108
Density is a measure of how much mass there is
in a given volume of a substance.
The flow that transfers heat within a fluid is called a
convection current.
Three Processes/forces combine to
set convection in motion:
1. Heating and cooling of a fluid,
2.changes in the fluid’s density,
3.force of gravity combine to set convection
currents in motion.
Inside Earth, large amounts of heat are transferred
by convection currents within the core and mantle.
Heat from the core and the mantle causes
convection currents in the mantle.
How Does Convection Occur in Earth’s Mantle?
Pg. 108
Convection Currents
What is Density?
Density is a measure of how much mass there is in a given
volume of a substance.
The flow that transfers heat within a fluid is called a convection
current.
Convection Currents pg. 108
-Heating and cooling of a fluid
-Changes in the fluid’s density AND
-The force of gravity
ALL Combine to set convection currents in motion!
Inside Earth, large amounts of heat are transferred by convection currents
within the core and mantle.
Heat from the core and the mantle itself causes convection currents in the
mantle.
Convection Currents in Earth pg. 109
Over millions of years, the great heat and pressure in the mantle
have caused solid mantle rock to warm and flow very slowly.
Many geologists think that 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.
Over and over, the cycle of rising and sinking takes place.
Convections currents like these have been moving inside Earth
for more than four billion years!
Did You Know?
Convection currents may form on planets other than Earth. For
example, scientists believe that the Great Red Spot on Jupiter
may be the result of storms that have convection currents.
Apply It! Pg. 108
Hot springs are common in Yellowstone National Park. Here, melted
snow and rain-water seep to a depth of 3,000 meters, where a
shallow magma chamber heats the rock of Earth’s crust. The rock
heats the water to over 200°C and keeps it under very high
pressure.
1. Compare and Contrast: The heated
Water is (more / less) dense than the
melted snow and rainwater.
2. Challenge: What might cause
convection currents in a hot spring?
The heated water rises to the surface.
As it rises, it cools, becomes more dense, sinks
Back down to the hot rocks, and is reheated.
Convection and the Mantle- Art in Motion pg. 109
Mantle Convection
Heat from the core and the
mantle itself causes
convection currents in the
mantle.
Describe the hot, convecting
Mantle by placing the
following words in the boxes
For points A and B.
hotter
Less dense
rises
colder
More dense
sinks
Assess Your Understanding pg. 109
1a. Explain: A convection current transfers (heat / air) within a
fluid.
b. Infer: in which parts of Earth’s core do convection currents
occur?
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c. Predict: What would happen to the convection currents in the
mantle if Earth’s interior eventually cooled down? Why?
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I get it! Now I know that convection currents in the mantle are
caused by __________________________________________.