Transcript Causal Loop Diagrams
Causal Loop Diagrams
Exponential growth of a bank account. The two positive connections between Bank balance and interest added for a positive feedback loop.
Causal Loop Diagrams
Earth’s Energy Balance. More absorbed sunlight increases Earth’s temperature. A warmer Earth sends off more heat radiation (a.k.a. longwave, infrared, or terrestrial) to space keeping our planet from getting too hot.
Earth’s albedo is the fraction of sunlight reflected back into space without being absorbed.
Connections (+ or - ??)
Remember use nouns
Absorbed Sunlight Planetary albedo Emitted Infrared Earth’s Mean Temperature Earth’s Mean Temperature Earth’s Mean Temperature Cloud Cover snow Cover Volcanic aerosol Planetary albedo Planetary albedo Water Vapor Planetary albedo Earth’s Mean Temperature CO2 Earth’s Mean Temperature Knowing the “sense” of connections between two system components is essential to understanding overall system behavior.
If when the first increases the second also increases the connection is positive.
If when the first increases the second also decreases the connection is negative.
Connections (+ or - ??) Answers
+ Absorbed Sunlight Earth’s Mean Temperature Planetary albedo Earth’s Mean Temperature Emitted Infrared Earth’s Mean Temperature Cloud Cover snow Cover Volcanic aerosol Water Vapor CO2 + or Earth’s Mean Temperature + Planetary albedo Earth’s Mean Temperature + Earth’s Mean Temperature + Earth’s Mean Temperature
Remember use nouns
Example
• Draw a causal loop diagram to describe the following: • The sun becomes brighter causing Earth to warm. As the Earth warms it gives off more longwave radiation until it settles into a new equilibrium temperature.
Example
• Draw a causal loop diagram to describe the following: • The sun becomes brighter causing Earth to warm to a new equilibrium temperature.
sunlight + Earth’s mean Temperature -
-
Emitted infrared energy +
Example
• Draw a causal loop diagram to describe the following: • The sun becomes brighter causing Earth to warm. As Earth’s surface warms it increases evaporation from the surface and adds water to the atmosphere which adds to the greenhouse effect.
Air Resistance
Connections (+ or - ??)
Size (area) of car Air resistance force Air resistance force Air temperature Speed of car Air resistance force
Remember use nouns
Air resistance Net downward Force weight
Connections (+ or - ??)
Size of parachuet Altitude Jumper’s speed Air resistance force Air resistance force Air resistance force Size of parachuet Altitude Jumper’s speed Net downward force Net downward force Net downward force
Remember use nouns
Draw a causal loop diagram to describe the following: As the sky diver falls she travels faster and faster until reaching a terminal velocity. Include diver’s speed, air resistance and net downward force in your diagram.
• Draw a causal loop diagram showing how a thermostat works.
Gas pedal depression car’s speed MPH above speed limit car’s speed