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