1. Systems 3

2. Feedbacks

3. Coffee System Tc TRTR The hotter the coffee is The faster it cools Tc-T R Cooling Rate The higher the cooling rate The colder the coffee Cooling Rate Tc-T R + -

4. Coffee System Tc TRTR The hotter the coffee is The faster it cools Tc-T R Cooling Rate The higher the cooling rate The colder the coffee - + - = -

5. Negative connection The higher the cooling rate The colder the coffee Cooling Rate Tc-T R - Tc TRTR

6. Positive connection The hotter the coffee is The faster it cools Tc-T R Cooling Rate + Tc TRTR

7. Negative feedback loop Tc TRTR The hotter the coffee is The faster it cools Tc-T R Cooling Rate The higher the cooling rate The colder the coffee - + - = -

8. Cools with a characteristic time constant,  minutes

9. Classic Positive Feedback

10. Positive Feedback

11. Thermostat

12. Domestic trouble ?? A husband and wife have an electric blanket that has his and her controls. The husband likes it warm and the wife likes it cold. It’s a very cold night out. What type feedback is it when they have the wrong controls?

14. A husband and wife have an electric blanket that has his and her controls. The husband likes it warm and the wife likes it cold. It’s a very cold night out. What type feedback is it when they have the wrong controls? A “positive” feedback loop

15. Domestic trouble ?? A husband and wife have an electric blanket that has his and her controls. The husband like it warm and the wife likes it cold. It’s a very cold night out. What type feedback is it when they have the correct controls?

16. A husband and wife have an electric blanket that has his and her controls. The husband like it warm and the wife likes it cold. It’s a very cold night out. What type feedback is it when they have the correct controls? Two separate negative feedback loops.

17. Equilibrium

18. Stable equilibrium (negative feedback)

19. Unstable equilibrium (positive feedback),

20. Perturbations Small changes that disturb a system from its equilibrium state. Hot Plate

21. A simple Earth Heating rate TETE

22. A simple Earth Heating rate TETE Albedo Absorbed solar Complete the system diagram

23. A simple Earth Heating rate TETE Albedo Absorbed solar Complete the system diagram + -

24. Daisy World Average surface Temp Daisy coverage TsDaisies Ts Daisies Albedo

25. Daisy World Average surface Temp Ts Daisies Daisy coverage TsDaisies

26. Daisy World Average surface Temp Ts Daisies Daisy coverage TsDaisies albedo P1P1 P1P1 Ts Daisies albedo P2P2 P2P2