1. Energy Systems & Climate Change Population Growth and Solar Motion Week 3, Fall 2009, The Evergreen St. College Dr. E.J. Zita & Dr. Cheri Lucas Jennings zita@evergreen.edu Lab II Rm 2272 http://academic.evergreen.edu/curricular/energy/0910

2. Plan for today: Cheri on cap and trade Zita on Ch.3 and solar motion (no brief reports until Thursday) 4:00 Plato lecture: Amy Stover

3. Milankovitch cycle drives ice ages? Eccentricity + Tilt + Precession

4. Changes in Earth’s motion → Glaciation http://www.globalwarmingart.com/wiki/Image:Milankovitch_Variations.png Need feedback mechanisms to push out of equilibrium

5. Why does the amount of solar energy Earth receives vary? 1.Does it matter where you are on Earth? 2.Does the time of year matter? 3.Consider Olympia: 1.When is it warmest? Why? Coolest? Why? 2.Where does the Sun rise? Where does it set? 3.Where is it at noon? 4.When is it directly overhead? 5.Does it ever shine on the north side of your house? 6.Your predictions or hypotheses?

6. Make your solar motion demonstrator

7. Test your hypotheses; note key points and surprises Sunrise is usually NE or SE, not due east Sunrise and sunset are due E and W only at Equinox (and on those dates, day and night are equally long at every latitude) The north side of a house in Olympia can get sunshine in the morning and evening all summer. The Sun is never directly overhead in Olympia – only in the tropics, and only one or two days a year. The path of the Sun depends on your latitude The rising/setting locations depend on the time of year Day length and temperature change more at the poles. You can find the length of the day with the model.

9. Q&A Q: How does path of the Sun depend on your longitude? A: It doesn’t – longitude simply fixes the timing of sunrise. Q. Would patterns be reversed in the S. hemisphere? Yes. Q: What are the different poles on Earth? A: Spin axis points at the North Star (for a few centuries.) The Magnetic axis is offset 11°, and wandering slowly. Q: What would the seasons be like if Earth’s tilt was different? A: More tilt → greater seasonal differences Q: How does the angle affect the brightness of sunlight? A: Steeper angle → dimmer sunlight.

11. Population & Growth (  P/time) Energy & Power (  E/time) Carbon & Emission (  C/time)

13. Calculate your energy use Q.3:For Monday Wolfson PIQs, post the energy-consumption rate (Watts) for five electrical devices you use every day. Also note the amount of time you use the device each day. We will compile class data and translate it into our partial energy use.

14. Post your energy-use data for Ch.2, Q.3 and Ex.4 in Moodle chart

15. Where to find Energy Use chart in Moodle

16. Now, where do we get our energy?

17. Compare US to world energy use

18. 1/Energy Intensity Energy intensity = energy use / GDP (kW/$1000)

19. Life expectancy increases with energy use – asymptotically Does GDP really measure quality of life?

20. Ch.2 + Seminar readings: Do Energy INTENSITY, energy USE, and/or GDP correlate with increased life expectancy? increased quality of life? increased happiness? Limits? Provisos? Inequalities?

21. We’ll do Ch.3 on Thursday Next: Plato lecture in LH 1 at 4:00

22. Zita’s office hours tomorrow 3:30-4:30 in 2242 Lab II (If we can’t get this space, we’ll leave a note saying where)