Causal Loop Diagrams Causal loop diagrams can be very helpful for explaining the mechanism behind feedback loops and identifying whether the feedback loop.
Post on 03-Jan-2016
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Causal Loop Diagrams
Causal loop diagrams can be very helpful for explaining the mechanism behind feedback loops and identifying whether the feedback
loop structure is a positive or negative feedback loop.
Earth’s Energy Balance is used here to develop and explain causal loop diagrams.
Connections (+ or - ??)*Absorbed 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
use nouns* A connection is positive if when the first increases the second also increases, and a connection is negative (opposite) if when the first increases the second decreases
Earth’s Mean TemperatureWater Vapor
Planetary albedo Earth’s Mean Temperature
Connections (+ or - ??)Absorbed 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
use nouns* The effect of cloud cover is complicated because they reduce sunlight be day but provide warming at night. High thin ciro stratus clouds also influence the Earth system differently than low thick stratus clouds.
Earth’s Mean TemperatureWater Vapor
Planetary albedo Earth’s Mean Temperature
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+ or
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.
Answer• 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+
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-+
Notice that the sun is not within the feedback loop structure.
This negative feedback loop is always present in the Earth System and helps limit the runaway effects of positive feedback processes.
Ice albedo feedbck process
Draw a causal loop diagram capturing the essence of the feedback process decribed below.
As Earth’s temperature increases from an increase in solar output there will be less snow and ice cover globally. This decreases the planetary albedo causing even more sunlight to be absorbed by the climate system resulting in amplified warming.
What are the polarities of each connection?
1.2.3.4.5.
What are the polarities of each connection?
1. +
2. -3. +
4. -5. +
What is the sign of this feedback loop?
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What is the sign of this feedback loop?
1. +
2. -3. +
4. -5. +
What is the sign of this feedback loop?
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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
Connections (+ or - ??)Size (area) of car Air resistance force
Air temperature Air resistance force**
Speed of car
Remember use nouns**Warmer air is thinner air
Air resistance force
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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
Connections (+ or - ??)Size of parachuet Air resistance force
Altitude Air resistance force
Jumper’s speed
Remember use nouns
Air resistance force
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Note: our text usesFor an opposite connection
o
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, weight, and net downward force in your diagram.
Whenever the number of negative (opposite) connection is oddThe loop is a negative feedback loop.
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