# Heat Transfer.

## Presentation on theme: "Heat Transfer."— Presentation transcript:

Heat Transfer

Heat transfer Everything is made of molecules.
When molecules gain energy they move faster and create more heat. (The faster the molecules move the hotter they are) Heat transfer Melting Evaporation Condensation Freezing liquid Solid Gas Molecules move very slowly! They are close together. Molecules move faster and are more spread apart. Molecules move very fast! They are very spread apart.

Heat Is the transfer of thermal energy from a hotter object to a cooler one until both objects are the same temperature. (You can not transfer cold or give someone cold) heat transfer video clip

On a hot sunny day, have you ever seen cars, buildings, or other objects appear to shimmer or waver on the other side of a street or parking lot? Explanation: Sun is heating up the ground more quickly than it heats the air, especially if the surface of the ground is a dark color. The heated air rises and bends light waves as it passes through them. Making the objects on the other side shimmer.

3 ways that heat is transferred within the atmosphere

The first method of heat transfer
How does heat energy get from the Sun to the Earth? RADIATION ?

The direct transfer of energy by infrared electromagnetic Waves.
Radiation What creates electromagnetic waves? Video clip 1 video clip 2 Eureka start at 2:30 The direct transfer of energy by infrared electromagnetic Waves. Sun, fire, light bulbs

Pair Share Partner A: What is radiation and where does it come from.
Partner B: What are three different things that create electromagnetic radiation?

Conduction conduction video clip 1 Eureka
The direct transfer of heat from one substance to another substance that is touching. Objects have to touch!!! Ironing Clothes Stepping on hot sand. That’s Hot

Conduction When you heat a metal strip at one end, the heat travels to the other end. As you heat the metal, the particles vibrate, these vibrations make the adjacent particles vibrate, and so on and so on, the vibrations are passed along the metal and so is the heat. We call this?

Conduction Example Stir your hot soup with a metal spoon
Pretty soon you need a pot holder because the end of the spoon you are holding gets hot This is heat transfer by conduction Energy travels up the spoon from the end in the hot soup to the end in your hand

Example of Conduction

Pair Share: Partner A: Using the picture on the right explain the conduction process Pair Share: Partner B: Explain how the picture on the left is conducting heat.

The transfer of heat by movement of a fluid (liquids and gases).
Convection convection video clip Convection 2 Convection- Eureka The transfer of heat by movement of a fluid (liquids and gases). Cooking peas in water Blow Drying your Hair. Dryer OVEN

The particles spread out and become less dense.
Convection What happens to the particles in a liquid or a gas when you heat them? The particles spread out and become less dense. This effects fluid movement. What is a fluid? A liquid or gas.

Water movement Cools at the surface Convection current Hot water rises
Cooler water sinks

Why do most refrigerators have the freezer on top
Why do most refrigerators have the freezer on top. Hint think about the principle of convection. Freezer compartment It is warmer at the bottom, so this warmer air rises and a convection current is set up. It is put at the top, because cool air sinks, so it cools the food on the way down.

Heating the troposphere
Radiation, conduction and convection work together to heat the troposphere. Radiation- heats the Earth Conduction- Air near earth’s surface is warmed Convection- the warm air molecules rise and transfer heat to the cooler air molecules. Eventually these molecules cool and sink back down to earth. This creates Convection Currents.

Radiation, Convection and Conduction work together to heat the troposphere.
review of all 3 types Radiation Convection Current Conduction

Radiation, Convection and Conduction work together to heat the troposphere.

Review Heat transfer from a hotter object to a cooler object until both objects are the same temperature. 3 types of heat transfer review, review 2 Music Review Radiation – electromagnetic waves Conduction – touching Convection- through a fluid (liquid or gas) All 3 work together to heat the troposphere but Convection causes most of the heating.