1. Heat and the Atmosphere

2. What do we Remember… Temperature Thermal Energy Heat
average of the kinetic energy of ALL the particles of a substance.
Thermal Energy
total kinetic energy of all the particles in a substance.
Heat
transfer of thermal energy

3. Heat Transfer: Conduction
Conduction is the transfer of thermal energy by direct contact.
Heat is transferred from high temperature, high kinetic energy particles to lower temperature, lower kinetic particles.
For example, a cold spoon warms when placed in a cup of hot coffee.
Thermal conductors transfer heat easily, while insulators do not.
Metals are good conductors
Good Insulators are: air, snow, wood and Styrofoam®

4. Heat Transfer: Convection
“Lava” cools down
- Molecules slow down, move closer together = INCREASE IN DENSITY
Convection is the transfer of heat energy in fluids (liquids and gases)
Convection is the movement of heat energy from hot to cold within a fluid, or the movement of hot liquid to an area of cool liquid.
NB: GASES ARE FLUIDS! (because they move!)
The “Lava” Falls
The “Lava” Rises
Heat from the light bulb warms the “lava”
- Molecules speed up, move further apart = DECREASE IN DENSITY

5. Convection Currents in the Earth’s Core
Huge chunks of land (called plates) float on top of these currents

6. Heat Transfer: Radiation
Radiation is the transfer of radiant energy by waves.
What we feel as heat is generally called infrared radiation.
Earth’s interior thermal energy comes from the core, plus some radioactive element decay.

8. The Earth’s Atmosphere and Heat Transfer
Earth’s atmosphere is a key factor in allowing life to
survive here.
This narrow band of air has the right ingredients, and maintains the correct temperature, to allow life to form and survive.
Originally, Earth’s atmosphere was very different, and had no oxygen.
Scientists think that oxygen first came from the breakdown of water by sunlight, then later by photosynthesis by plants.

9. The Earth’s Atmosphere and Heat Transfer
Despite what most people think, the Earth’s atmosphere is NOT made mostly of oxygen!
Air on Earth is 78% N2, 21% O2, 0.92% Ar, 0.04% CO2 and a variety of others.
The density of the atmosphere decreases with altitude (as pressure decreases)

10. The Earth’s Atmosphere: Layers
The Earth’s atmosphere is made of five layers:
Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere

11. A Closer Look: The Troposphere
Closest to Earth’s surface, 8 km - 16 km thick
Highest density layer because all other layers compressing it down.
Almost all water vapour in the atmosphere is found here.
Therefore, this is where most weather takes place.
Solar energy and thermal energy from Earth keep air moving
Temperatures range from average of +15ºC at the bottom to –55ºC at the top.

12. A Closer Look: The Stratosphere
The second layer
10 km to 50 km above Earth, warming from –55ºC as altitude increases
The transition from troposphere to stratosphere is called the tropopause.
The air is cold, dry and clean in the stratosphere.
Strong, steady winds, planes often fly here to avoid turbulent troposphere.
The ozone layer is found here, which blocks harmful UV radiation.
This is why the upper stratosphere warms more

13. A Closer Look: The Mesosphere
The mesosphere: 50 km to 80 km above Earth
This is the first layer in the “upper atmosphere”
Temperatures are as low as –100ºC
This layer is where space debris burns up when it begins to hit particles

14. A Closer Look: The Thermosphere
The thermosphere: 80 km to 500 km above Earth
Temperatures can reach +1500ºC to +3000ºC
This is where the Northern Lights, aurora borealis, are found.
Charged particles in Earth’s magnetic field collide with particles in the thermosphere

15. A Closer Look: The Exosphere
500 km to 700 km
Where the atmosphere merges with outer space
A Closer Look: The Exosphere

16. How Am I Supposed to Remember the Layers?
use a mnemonic
Exosphere = Excellent
Thermosphere = Thermos
Mesosphere = Makes
Stratosphere = Soup
Troposphere = Tasty

17. Your Turn! Make up your own mnemonic...
Exosphere = E ______________
Thermosphere = Th _____________
Mesosphere = M ______________
Stratosphere = S ______________
Troposphere = T ______________

18. So… what does the atmosphere have to do with heat transfer???

20. The Atmosphere and Conduction: Putting it All Together!
Almost all of the thermal energy on Earth comes from the Sun!
This is only a small fraction of the solar radiation that reaches Earth!
Most thermal energy is transferred near the equator, which receives a much more direct source of solar radiation (AKA. Insolation)

21. What is insolation? no not = insulation no not = insolent
no not = isolation

22. … why isn’t it all transferred?
Insolation = amount of solar radiation an area receives,
measured in W/m2
Insolation decreases if there are particles of matter (dust, smoke) in the way, or if the angle of incidence of the solar radiation is too great.
Angle of
incidence

23. More clarification please!!!
Angle of incidence = higher at the Earth’s poles = lower at the Equator
Sun’s rays hit the Equator more directly
= more solar radiation
= more insolation

24. The Radiation Budget Earth’s incoming radiation = outgoing radiation
if incoming radiation  outgoing radiation...Earth would heat up
if incoming radiation  outgoing radiation ...Earth would cool down

25. Solar radiation does not heat the atmosphere directly.
Earth’s surface absorbs solar radiation, heats up, then re-radiates the thermal energy into the atmosphere.
This provides 70% of the air’s thermal energy!
Convection in the air spreads the thermal energy around.

26. Albedo Albedo refers to the amount of energy reflected by a surface.
Light-coloured surfaces have a high albedo, and reflect energy (snow, sand)
Dark-coloured surfaces have a low albedo, and absorb energy (soil, water)

27. Use your notes to label the blanks on the “Important Figure” in your notes