• Most of the thermal energy at Earth’s surface comes

from the Sun.

• Half of the solar radiation that reaches Earth is

absorbed at the surface and converted to thermal

energy.

• The atmosphere and lithosphere

absorb thermal energy from the

Sun.

• The lithosphere is the

solid outer layer of Earth.

• The atmosphere is the layer

of gases enveloping Earth.

Earth’s Heat Sources14.3

VOCABULARY

lithosphere

atmosphere

troposphere

hydrosphere

albedo

• The albedo of a surface is the degree to which it reflects light.

• Earth’s interior has large quantities of thermal energy as a result of the planet’s formation and continuing radioactive decay.

• Earth’s hot core is well insulated because thermal energy cannot easily move through Earth’s lithosphere by conduction, convection, or radiation.

Earth’s Heat Sources14.3

VOCABULARY

lithosphere

atmosphere

troposphere

hydrosphere

albedo

ALBEDO CLIP: http://www.youtube.com/watch?v=lw8OpmHyal8

Heat and Thermal Energy Sources

• Thermal energy influences temperature, density, pressure, and a

substance’s physical state.

• Temperature is an indicator of the average kinetic energy of particles,

while thermal energy includes both kinetic energy and potential

energy from the motion of particles and their relative positions and

forces of attraction.

14CHAPTER

Heat and Thermal Energy Sources

• Heat is defined as the transfer of thermal energy from one object to

another because of differences in their temperature.

• Thermal energy can be transferred by conduction, convection, and

radiation.

14CHAPTER

Heat and Thermal Energy Sources

• Most of the thermal energy at Earth’s surface comes from the Sun.

• Earth’s interior has large quantities of thermal energy.

• The core is well insulated by land masses and is extremely hot as a result

of the planet’s formation and continuing radioactive decay.

14CHAPTER

Transfer of Energy on Earth

Activity• Take a look at Figure 3 on page 437. Discuss with your neighbour why

we have different seasons

• Can you predict what causes the seasons?

• What would have to occur for Earth to experience no seasons?

• Read “Reasons for the Seasons” on page 437 for more information.

15CHAPTER

Transfer of Energy on Earth15

Key Ideas• Atmospheric pressure results from gravity and the force of the

atmosphere pushing down on itself.

• Uneven heating of air produces differences in density and air

pressure.

• Wind results when air in high-pressure regions moves toward

regions with lower air pressure.

• Latitude and landscape influence the absorption of incoming

solar radiation.

• Global prevailing wind patterns influence ocean currents and

the formation of weather systems.

CHAPTER

• The force of gravity causes the atmosphere to exert significant pressure at Earth’s surface.• This is called atmospheric (or air) pressure.

• Atmospheric pressure decreases with altitude.

Atmospheric Pressure and Influences15.1

VOCABULARY

atmospheric pressure

kilopascal

low-pressure cell

high-pressure cell

isobars

• Air expands as it is heated, resulting in less dense, warm air with lower atmospheric pressure.• The warmer, less dense air floats up

through surrounding cooler, denser air which flows in underneath the rising air.

• Low-pressure cells contain warm, rising air with clouds and precipitation.

• High-pressure cells contain cool, falling air with little moisture.

Atmospheric Pressure and Influences15.1

VOCABULARY

atmospheric pressure

kilopascal

low-pressure cell

high-pressure cell

isobars

HIGH/LOW PRESSURE CLIP:http://www.youtube.com/watch?v=aiYyCurh_SU