3.2 Convection and the Mantle

Earth’s Structure and Materials- Course 2

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 gravityALL 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 heatedWater 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, sinksBack down to the hot rocks, and is reheated.

Mantle ConvectionHeat from the core and the mantle itself causes convection currents in the mantle.Describe the hot, convectingMantle by placing the following words in the boxesFor points A and B.

Convection and the Mantle- Art in Motion pg. 109

hotterLess denserises

colder

More densesinks

Assess Your Understanding pg. 1091a. 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 __________________________________________.