1. Earth’s Energy Budget

2. Modes of Energy Travel
Heat Energy can be transferred in three specific ways:
Conduction
Convection
Radiation

3. Heat Transfer
Conduction - transfers heat via direct molecular collision. An area of greater kinetic energy will transfer thermal energy to an area with lower kinetic energy. Conduction is the most common form of heat transfer and occurs via physical contact. Examples would be to place your hand against a window or place metal into an open flame. 

4. Heat Transfer
Convection – is heat transfer by mass motion of a fluid such as air or water when the heated fluid is caused to move away from the source of heat, carrying energy with it. As the immediate hot air rises, it pushes denser, colder air down.

5. Heat Transfer
Radiation – atoms emit electromagnetic waves. All materials radiate thermal energy based on their temperature. The hotter an object, the more it will radiate. The sun is a clear example of heat radiation that transfers heat across the solar system.

6. Solar Energy 71% absorbed 29% reflected
When radiant solar energy reaches the Earth, 2 different interactions occur:
Reflection – the radiation is reflected back into space unchanged
Absorption – the radiation is absorbed by the atmosphere of the Earth’s surface.
71% absorbed
29% reflected

7. Breakdown

8. Earth’s “Constant” Temperature
The Earth retains a relatively constant temperature.
To do this, it must lose as much energy back to space as it absorbs from the Sun. So we need to reradiate 71% of that energy back into space.

9. Balancing at the surface
For the energy budget at the Earth’s surface to balance, processes on the ground must get rid of the 48 percent of incoming solar energy that the ocean and land surfaces absorb.
Energy leaves the surface through three processes: evaporation, convection, and emission of thermal infrared energy.

10. Cont.
About 25 percent of incoming solar energy leaves the surface through evaporation.
An additional 5 percent of incoming solar energy leaves the surface through convection. The atmosphere is warmer near the surface and colder at higher altitudes, and under these conditions, warm air rises, shuttling heat away from the surface.

11. About 17 percent of incoming solar energy leaves the surface as thermal infrared energy (heat) radiated by atoms and molecules on the surface.

13. Energy and Water
Most of the sun’s energy hits water on earth (earth is 70% water)
Interactions between the sun’s energy and water have a major influence on weather but it depends on what state the water is in
White snow and ice reflect the vast majority of solar energy in the water world.

14. Energy and Water
Liquid water reflects only about 7% (i.e. it absorbs about 93%!!!)
Therefore the sun’s energy drives the water cycle, and in turn our weather.

15. Water in the Air
The incoming radiation from the sun causes ~23% of liquid water to evaporate
Evaporation occurs from all bodies of water but mostly the oceans
Water exists in the air as water vapour
When the air becomes saturated, condensation of the water vapour occurs (forms liquid water droplets) – this is called the DEW POINT
The amount of water vapour in the air is measured by humidity

16. Assignment
Using your notes, draw your own picture that shows the water cycle. Include the following terms:
Evaporation
Evapotranspiration
Condensation
Surface Runoff
Groundwater flow
Precipitation
Also add in the heat energy transfer you recorded in your notes – include incoming radiation and re-radiation of energy

17. Heating Earth
Why is it that when you are at the beach, the sand can be scorching hot while the water is cool?
After all they are getting the same amount of solar radiation

18. Specific Heat Capacity
Water is cooler because it has a higher specific heat capacity – meaning that it can absorb more heat before changing its temperature.
Specific heat is the amount of energy needed to raise the temperature of a certain mass by 1 degree Celsius.

19. Heating Dry Land vs Water
All sunlight that hits the sand or earth is absorbed in the top few cm making it 5 times as hot as water
All sunlight that hits water can be absorbed in layers much deeper thus making it cooler (think convection and conduction!).

21. Heating the Air
The first step is radiation – the sun’s energy warms the surface of the earth.
The second step is conduction
Conduction heats the air by hot (energized) water and land molecules transferring their heat (energy) to the surrounding air
The air directly above the land or water then becomes a similar temperature to the temperature of the water or land

22. Heating the Air The third step is convection
As the lower layers of air warm, it expands becoming less dense
Since it is less dense and warm, it rises and cooler air takes the place closer to the ground
Other substances in the air such as CO2 and H2O (g) can absorb sunlight and can cause temperature in the air to fluctuate

23. Heating the Air Uneven heating of the air causes wind
When cold air is located near warm air it pushes it upwards and creates wind

24. Sea Breeze

25. Sea Breeze Occur during the day Travel from sea to land How it works:
The land warms up faster than the water
This is due to water’s high specific heat capacity – it needs a lot of energy to warm up water
The warm air over the land rises while the cooler air over the water sinks down and moves in to replace it.
This cool air moving to the land causes the sea breeze!

26. Land Breeze

27. Land Breeze Occur at night Travel from land to sea How it works:
dry land cools faster than water
This is due to water’s large specific heat capacity (meaning it holds heat longer)
The air above the water is now warmer than the air above land. This warm air rises, while the cool air above the land falls and rushes over the water to take the place of the rising warm air.
The cycle continues, creating a land breeze.