- All things are made up of molecules
- When things get heated, they absorb heat energy
- With more energy, molecules are able to move faster
- When molecules move faster, the temperature rises
What is Thermal Energy
- Thermal Energy is energy resulting from the motion of particles
- It is a form of kinetic energy and is transferred as heat
- Thermal Energy Transfer can occur by three methods:
- Conduction
- Convection
- Radiation
Conduction
- Conduction is the transfer of thermal energy through direct contact between
particles of a substance, without moving the particles to a new location
- Usually occurs in solids
- When heat is supplied to one end, molecules at that end start to move more quickly
- In the process, they bump into their neighbors, transferring the kinetic energy
Convection
- Convection is the transfer of thermal energy through the movement of particles from one location to another
- Usually occur in fluids (liquids and gases)
- Example with boiling water:
- Water at bottom of the pan is heated first
- Heated water expands and density decreases
- Heated water begins to rise
- Cooler water with higher density from the sides of the pan rush down to take its place
- The cooler water gets heated and the cycle repeats
- We call these Convection Currents
Radiation
- Radiation is the emission of energy as waves or particles or rays
- Radiation does not require a medium to transfer energy
- Radiant energy is either reflected or absorbed by matter
- The energy that is absorbed increases the kinetic energy of the object
- This increases the temperature of the object
- Example … frying pan on a stovetop
- Energy is radiated from the heat source and absorbed by the lower surface of the pan
- For example… the sun
- Sun radiates energy in form of solar radiation
- When this energy reaches Earth, it is absorbed by matter (air, water, land)
- Absorbed radiant energy increases the kinetic energy of the matter, raising its temperature
- The sun is an emitter
- It gives out heat
- The Earth is an absorber
- It takes in the heat
Factors Affecting Radiation
ALBEDO
- Colour of the surface
- Albedo is the percentage of the incoming solar radiation that it reflects
- The albedo of Earth is about 30%
- Light-colored, shiny objects reflect more solar radiation and have a high albedo (ice, snow, sand)
- Darker, dull objects absorb more solar radiation and have a low albedo (forests, soils)
- Factors Affecting Radiation
- Surface Temperature
- The higher the surface temperature, the higher the rate of transfer
Surface Area
- The larger the surface area, the higher the rate of transfer
- Thermal Energy Transfer in the Atmosphere
- Things to Know:
- Atmospheric Pressure > the pressure exerted by the mass of air above any point on Earth’s surface
- Warm air is less dense than cold air
- Warmer regions generally have less atmospheric pressure than colder regions
- Wind > the movement of air from areas of high pressure to areas of low pressure
- The rising and sinking masses of air in convection currents cause changes in atmospheric pressure … causing wind
Wind Patterns and Coriolis Effect
- Moves from WEST to EAST
- Closer to the equator in colder months
- Closer to Poles in warmer months
- Thermal Energy Transfer in the Hydrosphere
- The effect of water on the transfer of heat is significant
- Earth’s climate is affected by phase changes in the water cycle
Water Cycle
- Water molecules undergo changes of state (e.g. solid to liquid)
- When these changes occur, thermal energy is either released or absorbed
- Released from liquid > solid
- Absorbed from Liquid > gas
- Temp. remains the same between phase changes
- Through changes of state is how thermal energy is transferred through the biosphere
Ocean Currents
- Main pathways to transfer thermal energy from warmer regions to cooler regions
- Global winds push the water, driving the surface currents of the ocean
- The pattern of ocean currents is modified by the Coriolis Effect
- Currents in North veer to the right
- Currents in South veer to the left
- Thermal energy is also transferred vertically via convection currents
- (same principles as with air)
@kenjay
What is your question?
This very great!!! I think I will take this unit on in April.
did not help at all
Why is it possible
You didn’t answer my question! 🙁
Same
This is very helpful!
This helped me understand more.
thanks, very helpful
well explained and thoroughly illustrated 👍👍
very useful
very useful.
what are the variables affecting solar energy transfer?
how does the transfer of thermal energy contribute to the formation of ocean currents. Explain???
had/have a paper to write and this didnt answer exactly what i needed..
This really helps!!!
This is good, it really helped. It is really informative. Wow!!!!!!!!!!!!!
Very useful
this helps me so much
Re: May.
What are you having trouble with in this subject matter?
this did not help at all!!!!! 🙁
didn’t help and i have finals tomorrow