The process of transferring heat to another

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1. HEAT TRANSFER:
CONDUCTION, CONVECTION AND
RADIATION

2. RadiationConduction
3 Ways Energy (Heat) is Transferred
Convection

3. Thermal Energy Transfer

Thermal energy transfer is heat moving from a
warmer object to a cooler object. This is
known as thermal energy transfer.

4. Terms to know:

Thermal Conductor – a substance that easily
passes thermal energy (heat) through it
(examples: metals)

Thermal Insulator – a substance that prevents
thermal energy (heat) transfer (example: wood,
plastic)

5. Heat is energy in motion (or transit).

It is the transfer of energy from a place of higher
temperature to a place of lower temperature.

Heat only moves toward the lower-temperature
body.

It is incorrect to say an object contains heat.
NOTHING contains heat.

Heat is a process (that’s used as a verb not a
noun)

Heat is not a “thing” but an energy transfer.

6. Heat transfer condition

Heat transfer occurs between states of matter whenever a
temperature difference exists and heat transfer occurs only
in the direction of decreasing temperature, meaning from a
hot object to a cold object.

Heat always moves from a warmer place to a cooler place.

Hot objects in a cooler room will cool to room temperature.

Cold objects in a warmer room will heat up to room
temperature.

7. How is Heat Transferred?
There are THREE ways heat can move.
Conduction
Convection
Radiation

8. CONDUCTION

Heat is transferred from one particle of matter to
another in an object without the movement of the
object.

Conduction = CONTACT

9. Have you ever…

Touched a metal spoon sitting in a pan of boiling
water only to be surprised by HOW hot it is??
Think back to what you know about metals and
nonmetals. What conducts heat better, metal or
nonmetal? Why?

10. Example of Conduction

Think of a metal spoon in a pot of water
being heated.

The fast-moving particles of the fire
collide with the slow-moving particles of
the cool pot.

Because of these collisions, the slower
particles move faster and heat is
transferred.

Then the particles of the pot collide with
the particles in the water, which collide
with the particles at one end of the
spoon.

As the particles move faster, the metal
spoon gets hotter. This process of
conduction is repeated all along the
metal until the entire spoon is hot.

11. EXAMPLE OF CONDUCTION

A piece of cheese melts as heat is transferred from
the meat to the cheese.

12. Convection Questions
Why does hot air rise and cold air sink?
Cool air is more dense than warm air, so the cool
air ‘falls through’ the warm air.
Why are boilers placed beneath hot water tanks in
people’s homes?
Hot water rises.
So when the boiler heats the water, and the hot
water rises, the water tank is filled with hot water.

13. CONVECTION
•Convection is the movement that transfers heat within
fluids and air (gas)
•Heat is transferred by currents within the fluid or gas
•Convection = VENTS (through air and liquid particles)
•Convection moves in
a circular pattern

14. Examples of Convection:

Have you ever noticed that the air near the ceiling is warmer
than the air near the floor? Or that water in a pool is cooler at
the deep end?

Examples: air movement in a home, pot of heating water.

Pick one of these examples and draw the circular pattern in
your notes.

15. RADIATION

Radiation is the transfer of
energy by electromagnetic
waves

Radiation does NOT require
matter to transfer thermal
energy

Radiation = Radiates (heat
escaping the sun)

16. Radiation May Come From Other Sources
Have you ever sat too close to a campfire while
cooking marshmallows? You’re enjoying the
warmth ….. only to notice that your skin is
really warm?

17. Examples of RADIATION
1.Fire
2.Heat Lamps
3.Sun

18. Radiation Questions
Why are houses painted white in hot countries?
White reflects heat radiation and keeps the house
cooler.
Why are shiny foil blankets wrapped around
marathon runners at the end of a race?
The shiny metal reflects the heat radiation from
the runner back in, this stops the runner getting
cold.

19. 3 Ways Energy (Heat) is Transferred
*Transferred in rays or
waves
*Energy from the Sun
warms the Earth
Example:
Reheating a cold cup of
coffee in a microwave
oven.
Example:
Heat transfers as the
barista “steams” cold
milk to make hot
 
cocoa.
Example:
Heat transfers into your
hands as you hold a hot cup
of coffee.
*Transfer of heat (energy)
that happens when
molecules bump into
each other
*Objects must be
touching
*”Conduction is touchin’”
*Transfer of heat by the flow
of material
*In warm air, the molecules
move apart, so it is less
dense and rises
*In cooler air, the molecules
move closer together, so it
is more dense and sinks

20. Energy is transferred between the Earth's surface and the
atmosphere in a variety of ways, including radiation,
conduction, and convection.

21. Conduction, radiation, and convection all play a role in moving heat
between Earth's surface and
 
the atmosphere. Since air is a poor
conductor, most energy transfer by conduction occurs right near Earth's
surface. Conduction directly affects air temperature only a few
centimeters into the atmosphere.
During the day, sunlight heats the ground, which in turn heats the air
directly above it via conduction. At night, the ground cools and the heat
flows from the warmer air directly above to the cooler ground via
conduction.
On clear, sunny days with little or no wind, air temperature can be much
higher right near the ground than slightly above it. Although sunlight
warms the surface, heat flow from the surface to the air above is limited
by the poor conductivity of air. A series of thermometers mounted at
different heights above the ground would reveal that air temperature falls
off rapidly with height.
Conduction in the Atmosphere

22. Any Questions?
Clarifications?

23. FOR
LISTENING