Slide 1UnitsSlide 3Slide 4Slide 5Slide 6Anthropogenic Methane SourcesSlide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 17Sudden Removal of all Greenhouse GasesSlide 19Slide 20Result: A Very Cold Planet!QuestionSlide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40Slide 41Slide 42Slide 43Slide 44Slide 45Slide 46Slide 47Slide 48Slide 49Slide 50MET 112 Global Climate Change - Lecture 2: Energy BalanceEnergy of EarthProfessor Menglin JinSan Jose State University, Department of MeteorologyUnitsUnits•Our class will use both English and Metric unit systems.•Most important:–Distance (kilometres and miles) –Temperature (ºC and ºF)•Conversions:1.6 km = 1 mile; 1 km = 0.61 miles(9/5 x ºC) + 32 = ºF(ºF – 32) x 5/9 = ºCClass Participation What is today’s minimum temperature? How much is it in °C ?99°F | 61°F Thursdayhttp://earthguide.ucsd.edu/earthguide/diagrams/energybalance/index.htmlUseful link on energy balance:Average Earth surface temperatureAnthropogenic Methane Sources•Leakage from natural gas pipelines and coal mines•Emissions from cattle •Emissions from rice paddiesMethane (CH4) is produced by anaerobic decay of organic material in landfills, wetlands, and rice fields; enteric fermentation in the digestive tracts of ruminant animals such as cattle, goats, and sheep; manure management; wastewater treatment; fossil fuel combustion; and leaks from natural gas transportation and distribution systems and abandoned coal mines. anaerobicDescribes an organism that is able to live without oxygen. Also used to describe environments that are devoid of gaseous or dissolved molecular oxygen.Question from last class: Why rice paddies produce Methane?http://www.learner.org/channel/courses/envsci/unit/text.php?unit=2&secNum=4http://en.wikipedia.org/wiki/Solar_radiation#Climate_effect_of_solar_radiationImportance of human-produced greenhouse gasesSource: Courtesy Marian Koshland Science Museum of the National Academy of Sciences http://www.koshland-science-museum.org.Balance: IN OUTEarthAt earth surfaceAt top of atmospheresince the Earth is much cooler than the Sun, its radiating energy is much weaker (long wavelength) infrared energy. energy radiation into the atmosphere as heat, rising from a hot road, creating shimmers on hot sunny days. The earth-atmosphere energy balance is achieved as the energy received from the Sun balances the energy lost by the Earth back into space. So, the Earth maintains a stable average temperature and therefore a stable climate. http://www.srh.noaa.gov/jetstream//atmos/energy.htmGreenhouse gasesEarth SurfaceSimply put, greenhouse gases trap long-wave radiation and keep such energy in the Earth-atmosphere system, so that earth-atmosphere warmsLongwave radiation is emitted from surface.Some surface radiation escapes to spaceMost outgoing longwave is absorbed in atmosphere (by greenhouse gases)Greenhouse gases emit longwave upward and downwardSome atmospheric radiation escapes to spaceSome atmospheric radiation is absorbed at the surfaceEnergy Balance•Assume that the Earth’s surface is in thermodynamic equilibrium:•Thermodynamic Equilibrium: –The flow of energy away the surface equals the flow of energy toward the surface SurfaceAverage surface temperature = 15°CRemoval of greenhouse gases would decrease downward flow of energy; now energy away from surface is greater than energy toward surface.Sudden Removal of all Greenhouse GasesRemoval of greenhouse gases would decrease downward flow of energy; now energy away from surface is greater than energy toward surface.Thus, average surface temperature starts to decrease.Sudden Removal of all Greenhouse GasesAs surface cools, emission of radiation decreases until balance is restored. At this point, cooling stopsSudden Removal of all Greenhouse GasesAs surface cools, emission of radiation decreases until balance is restored. At this point, cooling stops and equilibrium is restored.Average surface temperature = -18°CResult: A Very Cold Planet!Question•Start with the following diagram and assume the earth’s surface temperature is 15C and that the atmosphere has greenhouse gases.•Imagine that the concentrations of greenhouse gases were to increase by 50%. 1. Draw two more diagrams illustrating (with arrows) how the energy balance would change with the increase in greenhouse gases and explain why. •2. How would the average surface temperature change?SurfaceAverage surface temperature = 15°CClass Participation100% of the incoming energy from the sun is balanced by 100% percent total energy outgoing from the earth. incoming energy from the Sun = outgoing energy from the Earth.Details of Earth's energy balance (source: Kiehl and Trenberth, 1997). Numbers are in watts per square meter of Earth's surface, and some may be uncertain by as much as 20%. The greenhouse effect is associated with the absorption and reradiation of energy by atmospheric greenhouse gases and particles, resulting in a downward flux of infrared radiation from the atmosphere to the surface (back radiation) and therefore in a higher surface temperature. Note that the total rate at which energy leaves Earth(107 W/m2 of reflected sunlight plus 235 W/m2 of infrared] radiation) is equal to the 342 W/m2 of incident sunlight. Thus Earth is in approximate energy balance in this analysis.The Transfer Of HeatThe heat source for our planet is the Energy from the sun is transferred through space and through the earth's atmosphere to the earth's surface. Since this energy warms the earth's surface and atmosphere, some of it is or becomes heat energy. There are three ways heat is transferred into and through the atmosphere:radiation conductionconvectionsunRadiation is the transfer of heat energy through space by electromagnetic radiation.The flow of heat by conduction occurs via collisions between atoms and molecules in the substance and the subsequent transfer of kinetic energy.Take a look: http://www.nationmaster.com/encyclopedia/Image:Translational-motion.gifFig. 2-2, p. 30Convection is the transfer of heat energy in a fluid. Cumulus clouds indicates where upward convection currents areOther example: In kitchen liquid boilingTemperature•the degree of hotness or coldness of a body or environment (corresponding to its molecular activity) •Temperature is one of the principal parameters of thermodynamics. On the