energy transfer in the climate system · 2climatefactors (chp8).notebook 2 march 26, 2021 forms of...
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2ClimateFactors (Chp8).notebook
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Ch 8.1
Energy Transfer in the Climate System
Closed systemlThe Earth behaves like a closed climate system: matter is cycled through Earth (it’s not lost or gained)
lHowever, a closed system allows energy to transfer in/out of the system.
lHeat from the Sun enters and is eventually released back into spacelThe Earth must maintain a balance between intake and dispersion of energy
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Forms of energy transferlRadiationlConductionlConvection
RadiationlTransfer of energy through electromagnetic radiation.lDoes not require a medium for energy transfer.lCould be in the form of UV radiation, radio waves, X rays, gamma rays, or visible light.lMost of the energy from the Sun is short wave radiation (visible, UV, etc.)
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ConductionlTransfer of thermal energy through direct physical contact.lThermal energy goes from an area of higher temp to an area of lower temp.lE.g. conduction heats the air through collisions of molecules from the ground and air
ConvectionlTransfer of thermal energy through the movement of molecules from one place to another.lOnly occurs in liquids and gases.lE.g. warm air rises from ground and cool air falls to ground = wind
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Energy Transfer in the Atmosphere
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Energy Transfer in the OceanslWind creates currents at the surface to redistribute thermal energy (prevailing winds).lDeeper, colder currents move along ocean floor.
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Thermohaline Circulationocean circulation driven by wind, heat & salinity that mixes ocean water from the Arctic, Antarctic, Atlantic & Pacific Oceans.Cold water & salt water are dense – they sink & push warm less saline water upcontinuous twisting ocean currents move water from ocean surface to floor & around the planet carrying thermal energy around the Earth’s surface.
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Global Warming Disrupts Thermohaline Circulation
•increases rate at which ice melts, increasing the amount of fresh water which lowers northern ocean salinity – becomes less dense•increases rate of evaporation, increasing salinity in tropical oceans – becomes more dense•Polar water won’t sink disrupting thermohaline circulation•Affects upwelling vertical motion of ocean current that brings nutrients up from ocean floor•Many marine organisms that rely on this food source may be at risk
NASA global warming
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Weather Phenomena El Nino and La Nina
Periodic weather phenomena that have major global impacts
Video Link
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Greenhouse effect§Naturally occurring process that aids in heating the Earth's surface and atmosphere. §It results from certain atmospheric gases.
8.2
If you covered your solar cooker with a piece of plastic, you created a greenhouse effect (plastic replaces the CO2 in the system).
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Greenhouse gases (GHGs)GHGs: Absorb and reemit infrared radiation.
§Carbon dioxide (CO2)§Methane (CH4)§Nitrous oxide (N2O)§Ozone (O3)§Halocarbons ( CFCs – Chloroflourocarbons)§Water vapour
Composition of Earth’s Atmosphere§99% of Earth’s atmosphere is made up of nitrogen (N2) and oxygen (O2) – Fig. 8.12
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Global Warming Potential Not all compounds are equal
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Water vapour§Most abundant greenhouse gas responsible for 6585% of the greenhouse effect.§NOT added or removed from atmosphere by humans in significant amounts.§Concentration is directly affected by temperature. §i.e. higher temp’s = more evaporation = more water vapour in atmos. = absorb more thermal energy = warmer atmos.
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Carbon dioxide§Natural source – animal respiration
§Human sources –combustion of fossil fuels
–Deforestation = no photosynthesis and therefore no O2 produced
§Trees and oceans are important sinks for CO2–Sink: process that removes GHGs from atmos.
§Remedies – alternative energy sources, better forest management.
(more about this later)
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§ A 550kg cow produces between 800 to 1,000 L of emissions, including methane, each day.§ By changing a cow’s diet to include more alfalfa and clover and less grain, emissions can be reduced.
Methane§Formed during the breakdown of waste matter§Natural sources – wetlands, cattle§Human sources – decomposing garbage, processing coal and natural gas§Remedies – cattle wearing methane capture devices or providing an alternate diet with less meat consumption
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Ozone (O3)§Found in a concentrated layer in the stratosphere §Blocks harmful UV radiation§Has been decreasing since the 1970s§CFCs break down ozone (chlorofluorocarbons)
Fig. 8.16: Concentration of ozone over Antarctica decreased between 1979 and 2007. Largest ozone hole recorded: 29.5 million km2 (larger than North America!!)
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Ground Level Ozone§Ground level ozone = bad (smogforming pollutant).§Formed by the reaction of sunlight and vehicle exhaust.§Causes damage to lungs and heart.§Produces cracks in rubber and plastic.§Traps thermal energy close the Earth’s surface.
Vehicle exhaust is a direct source of GHGs, and an indirect source of groundlevel ozone.
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Anthropogenic Greenhouse Effect:–The increase in the G.E. because of an increase in GHGs introduced by human activities. Table 8.4
Greenhouse Gas Level before 1750 (ppm) 2005 Level 2021
Carbon dioxide 280 384 417
Methane 700 1745 1850
Nitrous oxide 270 314 410
CFCs 0 553
CO2 values real time link
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8.3 Cycling of Matter and the Climate System§Earth is a closed system – it contains a fixed amount of matter that does not increase or decrease.
§Matter is balanced through biogeochemical cycles: circulation of matter between biotic and abiotic factors.
Balance Disrupted
§Human activities, such as coal mining, oil drilling and burning of fossil fuels, alter the balance of natural cycles by rapidly releasing large amounts of materials from stores.
§Store: places within a biogeochemical cycle where matter is stored for longer periods of time.
§E.g. the atmosphere, oceans, land, marine sediments.
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Feedback Loopsfeedback loop process in which part of a system's output is returned, or fed back, to the input
positive feedback feeds itself and grows
negative feedback takes away from itself and shrinks
Positive Negative
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The Carbon Cycle§Carbon dioxide is added to atmosphere naturally via respiration and removed via photosynthesis.
§But carbon is found on Earth in other major stores/sink.§Marine sediments and sedimentary rocks.§Oceans§Fossil fuels (coal, oil, gas)§Vegetation, SOIL, and organic matter§Atmosphere
The Carbon Cycle
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The Global Carbon Budget§The relative amounts of carbon in different stores.
§Balanced Budget = CO2 into atm. = CO2 leaving atm.
§Human activities alter the balance of carbon in each store.
§E.g. carbon is stored in fossil fuels for hundreds of millions of years – after burning, carbon is released more quickly into a new store (atm) than would occur naturally.
The amount of CO2 put in the atmosphere by humans since the industrial revolution is called the "Legacy Load", and it is about 1000 Gigatons of CO2.
Think of a bank account, if you put in the same amount as you withdraw, the balance never changes. We have put a surplus of CO2 into our bank account, say +$1000, and if we want to get back to $0, we need to withdraw more than we deposit. This idea is called Drawdown.
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The Nitrogen Cycle§80% of the atmosphere consists of nitrogen gas (N2).
§In this chemical form, nitrogen cannot be used by living things – it must be converted into ammonium
(NH4+) or nitrate (NO3) via Nitrogen fixation.
§This occurs naturally by: lightning, bacteria found legume roots.§Fertilizers add an unbalanced amount of fixed nitrogen to soils (unnatural).
Lightning
Nitrogen gas is fixed into nitrates
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Task Handout
Nitrogen Fixing video1
2nd Half of Movie Inconvenient Truth