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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 - ??)
Absorbed Sunlight Earth’s Mean Temperature
Emitted Infrared Earth’s Mean Temperature
Cloud Cover
Volcanic aerosol
Earth’s Mean TemperatureCO2
Remember use nouns
Earth’s Mean TemperatureWater Vapor
Planetary albedo Earth’s Mean Temperature
snow Cover Planetary albedo
Planetary albedo
Planetary albedo
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 - ??) AnswersAbsorbed Sunlight Earth’s Mean Temperature
Emitted Infrared Earth’s Mean Temperature
Earth’s Mean TemperatureCloud Cover
Earth’s Mean TemperatureVolcanic aerosol
Earth’s Mean TemperatureCO2
Remember use nouns
Earth’s Mean TemperatureWater Vapor
Planetary albedo Earth’s Mean Temperature
+
-
+
+
-
-
-
+ or
snow Cover Planetary albedo+
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.
sunlightEarth’s mean Temperature
Emitted infrared energy+
-
-+
Air Resistance
Connections (+ or - ??)Size (area) of car Air resistance force
Air temperature Air resistance force
Speed of car
Remember use nouns
Air resistance force
weight
Air resistance
Net downward Force
Connections (+ or - ??)Size of parachuet Air resistance force
Altitude Air resistance force
Jumper’s speed
Remember use nouns
Air resistance force
Size of parachuet
Net downward forceAltitude
Jumper’s speed
Net downward force
Net downward force
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.
Gas pedal depression car’s speed
MPH above speed limit car’s speed
Home Heating
Home Heating
Home Heating