Unit 5 Part #1

1. Unit 5 Part #1 Fall 2012

2. The transfer of heat is normally from a high temperature to a lower temperature object. Water Current/Heat Transfer

3. Convection currents occurs wherever fluids are being heated. Here are some more examples: • Water in kettles • Soup in saucepans 
 • Water in a hot water tank • Convection even occurs in the Sun! Convection Everywhere

4. Convection is heat transfer by mass motion of a fluid such as air or water when the heated fluid is caused to move away from the source of heat, carrying energy with it. • Convection above a hot surface occurs because hot air expands, becomes less dense and rises • Hot water is less dense than cold water and rises causing convection currents Convection

5. Convection

6. Energy can be transported through a fluid (liquid or gas) by convection currents.. • The temperature of the water near the flame increases. This water expands and so its density is less than the water surrounding it. The higher temperature water therefore "floats" upwards transferring energy through the liquid. Convection in a liquid

7. Weather forecasters show how convection currents are formed when warm and cold air masses meet in the atmosphere. • Convection currents are responsible for warm water currents that occur in oceans. • This activity demonstrates convection currents in a very colorful way: • http://wm.kusa.gannett.edgestreams.net/news/1142952694628-03-21-06-spangler-inversion.wmv Convection in Our Atmosphere and Oceans

8. Mantle Convection

9. Convection occurs in gases and liquids. Hot fluids rise, cold fluids fall. • Convection currents occur because heat is lost from the rising fluid, cooling it down. • The whole fluid will rise in temperature as a result of mixing caused by convection currents. Convection Summary