1. 15.3 energy in the atmosphere
The Water Cycle Continues

2. Learning Targets
Describe how energy is transmitted
Describe the Earth’s heat budget and what happens to the Sun’s energy
Discuss the importance of convection in the atmosphere
Describe how a planet’s heat budget can be balanced
Describe the greenhouse effect and why it is so important for life on Earth

3. Energy All matter has energy Law of Conservation of Energy Many forms
All atoms are in constant motion
Law of Conservation of Energy
Energy cannot be created or destroyed
Examples: photosynthesis (solar chemical)
Many forms
Light, heat, motion, electrical, nuclear, etc.
For purposes of atmospheric energy – UV radiation, visible light, infrared

4. Transfer of Heat Energy
Through matter
Conduction – contact in solids
Convection – movement of heated particles in fluids
Radiation
Through empty space
Electromagnetic waves

6. Radiant Energy Radiation Ultraviolet (UV) Visible Infrared
High energy, damages DNA, shorter wavelength
Source: Sun, specialty lights
Visible
Energy we detect as light and color
Source: Sun, flashlight, candle
Infrared
Low energy, felt as heat, longer wavelength
Source: all matter above absolute zero
Shortest wavelength, most energy in visible light is violet. The next shortest wavelength is called ultraviolet.
Longest wavelength, least energy in visible light is red. The next longest wavelength is infrared.

7. More energy = faster movement = shorter wavelength

8. Solar Energy That Reaches Earth’s Surface
Ultraviolet
~7%
UVA, UVB, UVC
All UVC blocked by ozone
99% of UV blocked by ozone layer
Visible
~44%
Infrared
~49%
Solar heat
All of solar energy is broken down into three types of electromagnetic waves =100%

9. Shows what type of electromagnetic waves actually reaches the earth’s surface.

10. Solar Energy
What are some objects that appear to radiate visible light, but actually do not?
Reflection – When light (or another wave type) bounces back from a surface
Albedo – Measure of how well a surface reflects light (another wave type)

11. Temperature vs. Heat
Temperature is a measure of how fast the atoms in a material are vibrating
Heat is taken in or released when an object changes state of matter
Measures the material’s total energy
As temperature increases, the molecules vibrate faster, which generates heat.
Which has higher heat and which has higher temperature: candle flame or a bathtub full of hot water
Flame has higher temperature, but less heat, because the hot region is very small
Bathtub has lower temperature, but contains much more heat because it has many more vibrating atoms. Bathtub has greater total energy
Which do you think we care about when talking about the atmosphere – Temperature or Heat

12. Heat in the Atmosphere Moves mostly by convection Controlled by water
Weather and wind
It’s all about warm and cold water
Controlled by water
Latent heat
Absorbs/releases heat during phase changes
High specific heat
The quantity of heat absorbed or released by a substance undergoing a change of state, such as ice changing to water or water to steam, at constant temperature and pressure.

13. Latent Heat
A substance that is changing its state of matter does not change temperature. All of the energy that is released or absorbed goes toward changing the material’s state. Example – Pot of boiling water on a stove (100 degrees C). If you increase the temperature of the burner, more heat enters the water. The water remains at boiling temperature, but the additional energy goes into changing the water from liquid to gas.

14. Specific Heat
The amount of energy needed to raise the temperature of one gram of material by 1.00 C.
Water vs. Asphalt
The specific heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius. Water has a high specific heat meaning it takes the ocean longer to either get warmer or cooler. Land has a low specific heat, meaning it doesn’t take must heat to increase the temperature.

15. Solar Radiation on Earth
Insolation – differences in the amount of solar radiation that reaches a given area in a given time
Cause winds, affect climate, drive ocean currents
Solar radiation unevenly distributed
**Wind, precipitation, warming, and cooling depend on how much energy is in the atmosphere and where that energy is located. Much more energy from the Sun reaches low latitudes (equator) that high latitudes (poles)**

16. Seasons Caused by tilt of the earth on its axis Winter solar energy
Less direct
Fewer hours each day
More on this in other units

17. Tilt of Earth’s axis stays lined up with the North Star

22. Earth’s Heat Budget Absorb vs. Albedo
Albedo: measure of how well a surface reflects light (Reflection of Solar Energy)
Low albedo: dark soil or rock
High albedo: fresh snow
One exception: The Greenhouse Effect
About half of the solar radiation that strikes the top of the atmosphere is filtered out before it reaches the ground. Earth’s heat budget is balanced with the amount of energy that exits is = to the amount that comes in. Therefore, global temperatures stay the same.

23. About 3% of the energy that strikes the ground is reflected back into the atmosphere. The rest is absorbed by rocks, soil, water and then radiated back into the air as heat – The heat source for the troposphere is the Earth’s Surface.

24. What do you think global temperatures were like during the Ice Age and Why? The entire planet had high albedo effect, more energy was escaping than coming in.

25. Greenhouse Effect Warms troposphere
Infrared heat is reflected back to the surface
Don’t confuse with o-zone; UV reflects out to space
Natural process
May be affected by humans
Greenhouse gases
Methane, carbon dioxide, water vapor, CFCs
The warming of the atmosphere because of insulation by greenhouse gases is called the greenhouse effect.
The increase or decrease of greenhouse gases in the atmosphere affect climate and weather all over the world.
Is atmospheric nitrogen a greenhouse gas? NO