Home GEOG 205 Monday, January 13, 2012

Monday, January 13, 2012 CC-BY-NC
Lecture 3

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Lecture 3: Wednesday, January 18, 2012

Climate
• 30 year period
• long-term
• Earth: a system of interacting systems
• Hydrosphere: water systems, snow, rain, ice
• Biosphere: animals

Stefan-Boltzmann Law

• Energy = (constant) (temperature)^4
• Energy Units: Joules /sec m2 , or watts/m2
• Stefan-Boltzmann Constant:

• 342 W/m2 energy comes to Earth
• 47% absorbed
• 30% reflected and scattered (clouds, atmosphere)
• atmosphere increases the temperature on Earth
• most of the atmosphere is made of Nitrogen and Oxygen
• tropics are warmer because the sunlight hits at a more direct angle
• poles: same amount of energy but spread out more

• entropy(S): measure of the disorder of the system
• entropy of the universe is always increasing
• air rises, cools, and goes to pools
• Hadley and Fenel cells meet
• Winds are more North and South to equilibrate, Earth is also spinning at the same time
• Coupling is related to oceans and climates; sea temperature surface
• Land: only surface layer gets heated; cools and heats quickly
• Ocean: rays penetrate water which spreads out the heat (100m deep)

Conveyer Belt Circulation – Thermohaline Circulation
• North Atlantic: warm Gulf waters meet cool water, warm water evaporates and cools
• This increases the salinity (increases density) and it sinks to the bottom to the Southern Hemisphere and Alaska
• This process takes 500-1000 years
• Greenland’s fresh water ice melts, reduces salinity and water can rise again

Orthography/Topography
• Prevailing winds created from evaporation off warm ocean
• Warm, moist air (wind) travels off the ocean and cools
• Precipitates on the side of the mountain
• Reaches the top and the air is dry (rain shadow)
• Example: Vancouver vs. Alberta

Source, Stock, Sink
• Radiation transferred throughout Earth
• 99% of energy from sun to heat/evaporate
• NPP = Net primary production; all energy available to organisms (0.5% total from sun)
• 0.25% for respiration of plants
• NPP + respiration = GPP (gross primary production) = 0.75%

Global Carbon Budget
• Carbon Cycle
• Carbon is the 2nd most common GHG (1st is H2O(g))
• PG (petagrams) is 1015 g
• Atmosphere: 590 Pg/yr C
• Land, ocean, and atmosphere are about balanced between absorption of carbon and creation of carbon
• Fossil Fuel emissions: 5.4 Pg/yr C
• 3.4 Pg/yr C that are NOT being absorbed by the sinks

Equilibrium
• Dynamic equilibrium
• Example: long-term average temperature is the same, but we have cooler temperatures in the winter and warmer in the summer
• Dynamic dis-equilibrium: every year CO2 concentration goes up and down due to the seasons, but over the long-term it is increasing

Feedback
• Positive: response is amplified
• Negative: response is reduced
• Example: initial climate forcing, response is reduced/amplified by climate system
• Example: thermostat is negative feedback if it gets too hot
• Negative: photosynthesis vs. CO2 concentration
• Positive: temperature + respiration + CO2 concentation
• Negative: regular person + alcohol = I never want to drink again
• Positive: alcoholic person + alcohol = drinks more to delay hangover

Pertubations
• When something outside a system pushes it
• Example: waves made in a still pond by throwing a rock
• Volcano eruption caused decrease in temperature because the SO2 ash spread around the world and reflected the sun’s energy back to space
• El Nino’s: Southern ocean oscillation, warming of ocean
• Resilincy: the ability of a system to bounce back (over-fishing)

Temporal Scales
• Temperature over an hour, day, week, year
• Dynamic equlilbrium
• Make sure you know which time period you are looking at!