EquilibriumWelcome to DaisyworldFunctions and VariablesPhysical RelationshipsTemperature as a function of Daisy CoverageDaisy Coverage as a function of TemperatureEquilibrium PointsIn-class activityIn-class activityATMS211 CLIMATE CHANGEAnnouncements:1) The textbook for this class is now available on reserve at OdegaardLibrary (Ref: QH331 .K798).2) Bonus Credit OpportunityTV Program re US Policy on Climate Change:“Now” with Bill Moyers9-10pm Friday 23rdJanKCTS Seattle (PBS Stn, Channel 9)1 page description of the programEquilibrium“A state of a system in which forces, influences, reactions, etc balance each other out so that there is no net change”ORState of a system from which there is no tendency to change unless subjected to an external forcing.FEEDBACK LOOP:• count up the number of negative couplings• odd means "negative"• even or zero means "positive"Welcome to Daisyworld•Planet same size as Earth•No clouds•No greenhouse gases•1 species of plant:White DaisiesFunctions and VariablesDaisy coverage (C) is a function of surface temperature (T)C = f(T)Dependent variableIndependent variableT = f(C)Surface temperature (T) is a function of daisy coverage (C)Physical RelationshipsDaisy coverage (C) is a function of surface temperature (T)C = f(T)Life responds to temperature.There is an optimal temperature for daisy growth.Daisy coverage increases as you get closer tothat optimum. (and conversely...)T = f(C)Surface temperature (T) is a function of daisy coverage (C)Daisies are white, therefore reflect sunlight.Reflectivity (or "albedo") of planet responds to daisy coverage. Planetary temperature cools as more sunlight is reflected away. (and conversely...)Effect of Daisy coverage on TemperatureCT = f(C)0.90 00.86 20.82 40.78 60.74 80.70 100.66 120.62 140.58 160.54 180.50 200.46 220.42 240.38 260.34 280.30 300.26 320.22 340.18 360.14 380.10 40Temperature as a function of Daisy CoverageSimple Daisyworld00.20.40.60.81010203040Average Surface Temperature (T)Fractional Daisy Coverage (C) T = f(C)Daisy Coverage as a function of TemperatureSimple Daisyworld00.20.40.60.81010203040Average Surface Temperature (T)Fractional Daisy Coverage (C) C = f(T) coolC = f(T) warmEquilibrium Points-- Equilibrium Points -TCcool 12.9 0.64warm 36.7 0.17Simple Daisyworld00.20.40.60.81010203040Average Surface Temperature (T)Fractional Daisy Coverage (C) C = f(T) coolC = f(T) warmT = f(C)In-class activityDaisyworld00.20.40.60.810 10203040Average Surface Temperature (T)Fractional Daisy Coverage (C) C = f(T) coolC = f(T) warmT = f(C)SurfacetemperatureDaisycoverageSurfacetemperatureDaisycoverageCool Climate Regime Warm Climate RegimeIn-class activityDaisyworld00.20.40.60.810 10203040Average Surface Temperature (T)Fractional Daisy Coverage (C) C = f(T) coolC = f(T) warmT = f(C)SurfacetemperatureDaisycoverageSurfacetemperatureDaisycoverageCool Climate Regime Warm Climate Regime2 negative couplings (even)positive feedback loopUNSTABLE1 negative coupling (odd)negative feedback
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