Convection, Conduction, and RadiationHeat Transfer

Review of Density Warmer temperatures = less density Cooler temperatures = higher density

Density and MotionHow does this happen?

Look at the example:

If these 2 arrows come together, will they move?

Why or why not?

10 10

No movement!

Density and MotionNow 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

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!)

Don’t forget! High amount of molecules = cooler

temperatures

Low amount of molecules = warmer temperatures

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

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

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

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

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

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

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?

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?

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