Earth System (3 days)

- Equilibrium and stability [
**System Behavior and Causal Loop Diagrams**(ch-1.pdf, 197,271 bytes)] - Causal loop diagrams [Causal Loop Diagram Tutorial, Dinosaur Extinction: Causal Loop Diagram of Earth Feedback ...]
- Positive and Negative Feedback processes [See Systems Thinking overview above][ Basic Feedback Structures ]
- Delays [ Delays, Smoothing, and Averaging ] [slide 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

**Learning Excel Basics
[Activity] **Due Sept 4**
**

Key terms and study questions:

Chapter 1 of Earth's Climate Text (all key terms), Review Questions 4 , 5 and 7

Chapter 4 [Key terms: Faint Young Sun paradox, thermostat, Gaia hypothesis, homeostasis. Review questions 1-5]

**Interactive lecture questions.**

What is a System?

Choose one of the following systems. Describe its different elements and how they interact with each other in terms of feedback:

· quitting smoking

· procrastination

· learning a new skill

· dieting

· studying/goofing off

Draw a causal loop diagram describing your system.

Negative Feedback: Describe a system with self regulating behavior.

Draw a causal loop diagram describing your system.

Positive Feedback: Discuss the explosive growth of the internet by identifying its positive feedback loops.

Is there a limit to the internet growth? If so discuss some of the limiting factors.

Negative feedback: The heating rate in degrees C per minute (DT/Dt)
of a pot of water set on a warm (30 ^{o}C) room is DT/Dt=-0.5*(T-30),
where T is the temperature of the water.

Assume that the water starts at 50 ^{o}C, find its temperature at 1,
2, 3, and 4 minute. Sketch this on a graph with T on the y-axis and
time on the x-axis.

Assume that the water starts at 10 ^{o}C, find its temperature at 1,
2, 3, and 4 minute. Sketch this on the same graph with T on the
y-axis and time on the x-axis.

Positive feedback. An interest rate of 10% on your savings account
balance, B, means that your savings increases at a rate of 10% per year.

DB/Dt=0.10*(B)

Starting with $1000.00 find the balance after 1, 2, 3, 4, 5, 6, and 7 years. Sketch this on a graph with B on the y-axis and time on the x-axis.

How long does it take your balance to double?

Starting with $1000.00 and using a 20% interest rate find the balance after 1, 2, 3, and 4years. Sketch this on the same graph with B on the y-axis and time on the x-axis.

How long does it take your balance to double?