PERFORMANCE OBJECTIVES:

Given the relevant information, you will:

1.  Describe the three methods of heat transfer.

2.  Give examples of the three methods of heat transfer.

3.  Describe how heat effects the movement of air.

4.  Recognize how convection currents heat our homes.

5.  Recognize how convection currents effect liquids and weather.

The performance objectives are aligned with the following MCAS standards:

ACTIVITY #1:

       Read the following information.

How does heat get around?  Heat is not matter.  It is energy that can change into other forms.  On its own, it travels by three basic methods:  Convection, Conduction and Radiation.

The movement of heat from a warmer object to a cooler one is called heat transfer. There are three methods of heat transfer.  Heat is transferred by Convection, Conduction and Radiation.

Convection                                                            

       Heat travels through air.  Cold air is heavier than warm air.  When cold and warm air meet, the cold air sinks below the warm air and forces the warm air to move upward. 

  WARM AIR RISES

      Heat from a wood stove in the first floor living room rises and warms the second floor bedrooms.  The heating ducts, radiators and baseboard heat at your house are located on the floor so the heat will rise and warm the whole room.  The warm air carries its heat upward as it rises.  This is one way heat travels through air.  It is called CONVECTION.  The sinking cool air and rising warm air moves heat.  These up and down movements of the air are called convection currents.

CONVECTION CURRENTS IN LIQUIDS

     Convection also takes place on liquids.  Cold water is heavier than warm water.  Cold water moves down and warm water moves up.   Boiling water in a pan moves in convection currents. 

      Think about diving into lake water or a deep swimming pool.  Is the water on the bottom colder than the water near the top?  Cold water is heavier than warm water;  cold sinks, warm rises.  The sinking and rising of air and water produce convection currents.  These currents transfer heat.

     The air currents in the earth's atmosphere, which contribute to our weather, are caused by convection currents.  If it is warm during the day the air rises forcing cool air to sink, this movement produces wind which brings in new weather.

ACTIVITY #2:

     Complete the following sentences by filling in the blanks.

     1.  Warm air ______________________________

     2.  Cold air _______________________________

     3.  The movement of cold and warm air produces convection ________________________________

     4.  When cold and warm air meet, the cold air sinks below the warm air and this forces the warm air ________________

     5.  Radiators, heat ducts and baseboard heaters are located on the _________________________________

     6.  The movement of warm air upward forcing the cool air to sink produces __________ which brings in new _________

     7.  The temperature of water on the bottom of the lake is _____________ than the temperature of the water at the top.