Convection, Conduction, and Radiation

1. Convection, Conduction, and Radiation Heat Transfer

2. Review of Density • Warmer temperatures = less density • Cooler temperatures = higher density

3. Density and Motion How does this happen? Look at the example: If these 2 arrows come together, will they move? Why or why not? 10 10 No movement!

4. Density and Motion Now look at this example. If these 2 arrows came together, what would happen? 10 5 Movement! The values are not equal & the movement will be in the direction of the bigger force

5. Density Poem “Motion will go from high to low” Meaning: the molecules will go from where there are a lot to an area where there are few Equilibrium: when molecules are equal on both sides (no movement!)

6. Don’t forget! • High amount of molecules = cooler temperatures • Low amount of molecules = warmer temperatures

7. Motion and atmosphere • Cool air sinks (more dense) • Warm air rises (less dense) Motion: Creates a circular motion: heats up goes up, cools off comes down, heats up goes up, cools off comes down

8. Motion in water • Cool water sinks (more dense) • Warm water rises (less dense) Motion: Creates a circular motion: heats up goes up, cools off goes down, heats up goes up, cools off goes down

9. Motion under the Crust • Cool magma sinks (more dense) • Warm magma rises (less dense) Motion: Creates a circular motion: heats up goes up, cools off comes down, heats up goes up, cools off comes down

10. What causes those fluids to heat up? Radiation (aka a heat source) Natural Radiation: The Sun, the center of the earth, fire Artificial Radiation: hot plate, burner on stove, candle

11. Conduction • When the radiation gets transferred to an object, that is called conduction • 2 objects must be in contact with each other • Objects can be as small as electrons Examples: touching a hot spoon, sitting on leather seats in the summer, feeling the counter when the sun is out

12. Convection Currents • This is the circular movement of the heat transfer • This is an action, a verb, a “doing” • Molecules will flow to different levels of concentrations: from high to low

13. Which temperature has more molecules in a given space? • Cooler/Cold • Cooler temperatures = increased density • Think about the molecules packed together in ice • What type of temperature outside will have greater density: hot weather or cold weather?

14. Which temperature has less molecules in a given space? • Warmer/hot • Increased temperatures = decreased amount of molecules in the same area • Think about how the molecules would look like in a gas  all spread out • What type of temperature outside would have lower density: hot weather or cold weather?

15. Summary of CCR: • Radiation: EM radiation from the Sun heats up the ground or water • Conduction: transfer of heat to touching molecules • Convection: the different densities of temperature create a circular movement: from high to low