• 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