UNIT THREE: Matter, Energy, and Earth



Chapter 8 Matter and Temperature



Chapter 9 Heat



Chapter 10 Properties of Matter



Chapter 11 Earth’s Atmosphere and Weather

Chapter Nine: Heat



9.1 Heat



9.2 Heat Transfer

Chapter 9.2 Learning Goals



Compare and contrast various methods of heat transfer.



Differentiate between thermal conductors and thermal insulators.



Explain what it means when objects are in thermal equilibrium.

Investigation 9B

Convection in Earth’s Atmosphere 

Key Question:

How is convection responsible for the movement of air through the atmosphere??

9.2 Heat transfer



Thermal energy flows from higher temperature to lower temperature. This process is called

heat transfer

.

   

There are three ways heat flows:

heat conduction

,

convection

, and

thermal radiation

.

9.2 Heat transfer



Heat conduction

is the transfer of heat by the direct contact of particles of matter.

Where is the heat energy conducted to and from in this system?



Conduction occurs between two materials at different temperatures when they are touching each other.

9.2 Thermal Equilibrium



When both materials are at the same temperature, they are in

thermal equilibrium

.



No heat flows when objects are in thermal equilibrium.

9.2 Thermal conductors and insulators



Materials that conduct heat easily are called

thermal conductors

and those that conduct heat poorly are called

thermal insulators

.

Is a down coat a conductor or an insulator?

9.2 Convection



Convection

is the transfer of heat through the motion of matter such as air and water.



The hot water at the bottom of the pot rises to the top and replaces the cold water.

9.2 Convection



Convection is mainly what distributes heat throughout a room.

9.2 Thermal radiation



Heat from the Sun is transferred to Earth by

thermal radiation .



All the energy the Earth receives from the Sun comes from thermal radiation.



The higher the temperature of an object, the more thermal radiation it emits.

9.2 Thermal radiation



Thermal radiation is also absorbed by objects.



The amount of thermal radiation absorbed depends on the surface of a material.



Dark surfaces absorb most of the thermal radiation they receive.



Silver or mirrored surfaces reflect thermal radiation.

9.2 Heat transfer, winds, and currents

  

A

thermal

is a convection current in the atmosphere. When a surface, like a road absorbs solar radiation, it emits energy as heat. The warmed air molecules gain kinetic energy and rise.



Colder air is forced aside and sinks.

9.2 Thermal radiation



There are giant convection currents in Earth’s atmosphere.



The global wind patterns and Earth’s rotation also cause surface ocean currents to move in large circular patterns.

Needed: Efficient Buildings



“Green” building design is the term used to describe architecture that is energy efficient and environmentally friendly

.