1. in the Atmosphere
Heat Transfer
©2008 Norm Ivey

2. What is Heat Transfer?
Heat transfer is the movement of heat energy from one substance to another.

3. What is Heat Transfer?
Heat (energy) always moves from a warmer substance to a cooler substance.
Hot
Cold

4. What is Heat Transfer?
Heat will continue to move until both substances are the same temperature.
Warm
Hot
Warm
Cold

5. What is Heat Transfer?
The greater the difference in temperature between the substances, the faster the heat will transfer.

6. What is Heat Transfer? There are three types of heat transfer:
Conduction
Convection
Radiation

7. Examples Anti-Examples
You touch a black car in the summer and the heat from the car transfers into your hand.
A breeze makes you feel cooler because the wind transfers heat away from your body.
You feel the cold of a winter day because the cold air transfers into you.
Your Coke in a cooler gets cold because the cold from the ice moves into the Coke.

8. Conduction
Heat transfer by conduction is the transfer of heat through direct contact.

9. Conduction
Molecules transfer energy to the molecules next to them.

10. Conduction The molecules do not have to be the same substance.

11. The metal conducts heat from the cup
Example 1
The metal conducts heat from the cup
of warm water to the cup of cool water.

12. Your Coke becomes cold because the heat from the soda
Example 2
Your Coke becomes cold because the heat from the soda
transfers into the ice, not the other way around.

13. No matter what it feels like, cold does not transfer into your body.
What is really happening here?
Why do you wear heavy clothes when it’s cold outside?

14. Radiation
Heat transfer by radiation is the transfer of heat through electromagnetic waves.

15. Radiation
There is no direct contact between the substances.

16. Heat from the sun radiates through
Example 1
Heat from the sun radiates through
empty space to earth.

17. The heat from the campfire transfers
into your marshmallow, giving you a yummy, gooey treat!
(Direct contact between the fire and your marshmallow will ruin it!)
Example 2

18. Convection
Heat transfer by convection is the transfer of heat through the fluid (liquids and gases) movement of currents.

19. Convection
Warm fluids rise, cool down, sink, and then are warmed again.

20. The radiator warms the room by warming the
The radiator warms the room by warming the
air around it. Then the warm air transfers heat
to the rest of the room through convection.

21. As air above the road warms up, it rises and is replaced by
cooler air, forming a convection current.

22. This picture illustrates all three type of heat transfer.
Conduction
Convection
Radiation
This picture illustrates all three type of heat transfer.
Can you identify them all?