Thermal energy is the total energy of motion of the particles of a substance.

16-2 Heat Transfer

(pages 548–551)

1. Describe how temperature is measured.2. Identify three ways in which heat is transferred.3. Explain how heat is transferred in the troposphere.

Thermal Energy and Temperature (page 549)

1. Describe how temperature is measured.

Key Concept: Air temperature is usually measured with a thermometer.

The temperature of something is a measure of the motion of its particles. Temperature is the average amount of energy in the motion of each particle of a substance.

Thermal energy is the total energy of motion of the particles of a substance.

A thermometer is an instrument that measures temperature.

Temperature is measured in units called degrees. Two temperature scales are the Celsius scale and the Fahrenheit scale. Scientists use the Celsius scale.

1. Read each word in the box. In each sentence below, fill in the correct word or words.

a. An instrument that measures temperature is

called a .

b. The total energy of motion of the particles of a

substance is the of the substance.

temperature

thermometer

thermal energy

thermometer

thermal energy

1. Is the following sentence true or false? Scientists use the Fahrenheit scale to measure temperature.

.

How Heat Is Transferred (pages 550–551) false

How Heat Is Transferred (pages 550–551)

2. Identify three ways in which heat is transferred.

Key Concept: Heat is transferred in three ways: radiation, conduction, and convection.

Most of the heat you feel from the sun travels to you as radiation. Radiation is the direct transfer of energy by electromagnetic waves. Radiation does not need matter to travel through. It can travel through empty space.

Conduction is the direct transfer of heat from one thing to another. Transferring heat by touching is an example of conduction. When you walk on hot sand, your feet get hot by conduction.

Convection is the transfer of heat by the movement of a fluid. A fluid is a liquid or a gas. The particles of a fluid take heat with them as they move. If you heat the air in one room, the air will heat the next room as the air flows from one room to the next. This is heating by convection.

Answer the following questions. Use your textbook and the ideas above.

1. Draw a line from each term to its meaning.

Term

radiation

conduction

convection

Meaning

a. the direct transfer of heat from one thing to another

b. the direct transfer of energy by electromagnetic waves

c. the transfer of heat by the movement of a fluid

1. Read each word in the box. Use the words to complete the table about examples of heat transfer.

Examples of Heat Transfer

Type of Heat Transfer Example of Heat Transfer

a. hot water swirling in a pan

b. warming your hands in front of a campfire

c. putting an electric heating pad on your knee

d. feeling the sun’s heat on your face

Key Concept: Radiation, conduction, and convection work together to heat the troposphere.

• Sunlight heats Earth’s surface by radiation. The warm surface then heats the atmosphere by both conduction and radiation.

radiation conduction convection

convection

radiation

conduction

radiation

3. Explain how heat is transferred in the troposphere.

Key Concept: Radiation, conduction, and convection work together to heat the troposphere.

Sunlight heats Earth’s surface by radiation. The warm surface then heats the atmosphere by both conduction and radiation.

Only the first few meters of the troposphere are heated by conduction. The air closer to the ground is usually warmer than the air above it.

Heat is transferred by convection through most of the troposphere. Convection currents move heat throughout the troposphere. The upward movement of warm air and the downward movement of cool air form convection currents.

Answer the following questions. Use your textbook and the ideas on page 257.

1. Is the following sentence true or false? Earth’s atmosphere is heated by only conduction and radiation.

2. The picture shows all three types of heat transfer working together to heat the troposphere. Draw a circle around heat transfer by convection.

3. The upward movement of warm air and the downward movement of cool

air form .

false

1. The upward movement of warm air and the downward movement of cool

air form . convection