1. MET 112 Global Climate Change - Lecture 2: Energy Balance Energy of Earth Professor Menglin Jin San Jose State University, Department of Meteorology

2. Units 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 = ºC

3. Class Participation What is today’s minimum temperature? How much is it in °C ?99°F | 61°F Thursday

4. http://earthguide.ucsd.edu/earthguide/diagrams/energybalance/index.html Useful link on energy balance:

6. Average Earth surface temperature

7. Anthropogenic Methane Sources Leakage from natural gas pipelines and coal mines Emissions from cattle Emissions from rice paddies

8. Methane (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.anaerobicruminant anaerobic Describes 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=4

9. http://en.wikipedia.org/wiki/Solar_radiation#Climate_effect_of_solar_radiation

11. Importance of human-produced greenhouse gases Source: Courtesy Marian Koshland Science Museum of the National Academy of Sciences http://www.koshland-science-museum.org.

12. Balance: IN OUT Earth At earth surface At top of atmosphere

13. since 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.htm

14. Greenhouse gases Earth Surface Simply put, greenhouse gases trap long-wave radiation and keep such energy in the Earth-atmosphere system, so that earth-atmosphere warms

15. Longwave radiation is emitted from surface. Some surface radiation escapes to space Most outgoing longwave is absorbed in atmosphere (by greenhouse gases) Greenhouse gases emit longwave upward and downward Some atmospheric radiation escapes to space Some atmospheric radiation is absorbed at the surface

16. Energy Balance Assume that the Earth’s surface is in thermodynamic equilibrium: Thermodynamic Equilibirum: –

17. Energy 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 Surface Average surface temperature = 15°C

18. Removal 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 Gases

19. Removal 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 Gases

20. As surface cools, emission of radiation decreases until balance is restored. At this point, cooling stops Sudden Removal of all Greenhouse Gases

21. As surface cools, emission of radiation decreases until balance is restored. At this point, cooling stops and equilibrium is restored. Average surface temperature = -18°C Result: A Very Cold Planet!

22. 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? Surface Average surface temperature = 15°C Class Participation

23. 100% 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.

24. Details of Earth's energy balance (source: Kiehl and Trenberth, 1997).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.

25. The Transfer Of Heat The 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 conduction convection sun

26. Radiation is the transfer of heat energy through space by electromagnetic radiation.

27. 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.gif

28. Fig. 2-2, p. 30

29. Convection is the transfer of heat energy in a fluid. Cumulus clouds indicates where upward convection currents are Other example: In kitchen liquid boiling

30. Temperature 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.thermodynamics On the microscopic scale, temperature is defined as the average energy of microscopic motions of a single particle in the system per degree of freedom.degree of freedom On the macroscopic scale, temperature is the unique physical property that determines the direction of heat flow between two objects placed in thermal contact. Cold temperature Warm temperature

31. Units 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 = ºC

32. Three temperature scales: KelvinKelvin CelsiusCelsius FahrenheitFahrenheit What does temperature mean physically?What does temperature mean physically? see next page see next page What does 0° K mean?What does 0° K mean?

33. Three temperature scales: KelvinKelvin CelsiusCelsius FahrenheitFahrenheit What does temperature mean physically?What does temperature mean physically? What does 0° K mean?What does 0° K mean? °K= °C+273 Absolute zero (see next page)

34. Temperature Definition 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.thermodynamics On the microscopic scale, temperature is defined as the average energy of microscopic motions of a single particle in the system per degree of freedom.degree of freedom On the macroscopic scale, temperature is the unique physical property that determines the direction of heat flow between two objects placed in thermal contact.

35. kelvin temperature scale (Abbreviated K; also called absolute temperature scale, thermodynamic temperature scale). An absolute temperature scale independent of the thermometric properties of the working substance. (http://amsglossary.allenpress.com/glossary) a change of 1 Kelvin equals a change of 1 degree Celsius; absolute zero - 0ºK is the lowest temperature on the Kelvin scale. The freezing point of water is +273ºK (Kelvin) and the boiling point of +373ºK ice point of pure water defined as 273.16K Absolute zero is where all kinetic motion in the particles comprising matterkinetic ceases and they are at complete rest in the “classic” (non-quantum mechanical) sensequantum mechanical

36. The size of the degree is the same as on the Celsius scale SI unit of temperature is K

37. As a system receives heat, its temperature rises; similarly, a loss of heat from the system tends to decrease its temperature When two systems are at the same temperature, no heat transfer occurs between them. When a temperature difference does exist, heat will tend to move from the higher-temperature system to the lower-temperature system, until they are at thermal equilibrium. This heat transfer may occur via conduction, convection or radiation orconductionconvectionradiation combinations of them

38. The role of Temperature in nature What is air temperature in this image? the frost shown here is at -17 °C.

39. Many physical properties of materials including the phase (solid, liquid, gaseous or plasma), density, solubility,phasesolidliquidgaseousplasmadensitysolubility vapor pressurevapor pressure, and electrical conductivity depend onelectrical conductivity the temperature. What weather conditions depend on air temperature? Temperature also plays an important role in determining the rate and extent to which chemical reactions occurchemical reactions

40. MODIS daytime (10:30am) T skin in October Global surface temperature vary with location (Jin and Dickinson 2008)

41. MODIS 7 year averaged (2000-2007) Improve Understanding of Surface Temperature July January

42. Sea Breeze: determined by air-surface temperatures Source: Adapted from graphic by National Oceanic Atmospheric Administration, Jet Stream. Example of Importance of surface temperature

43. Skin Temperature May July seasonality

44. Diurnal Variation of Surface Temperature

45. NASA EOS MODIS Observed Surface Temperature Nighttime MODIS T skin Oct 2007 (10:30 pm)

46. Daytime Higher T skin in GFS than MODIS at the western part and mountain peaks GFS T skin Oct 2007 (10:30 am)MODIS T skin Oct 2007 (10:30 am) 4. Evaluate NOAA GFS T skin Simulation Using MODIS

47. Temperature controls many things, including the availability of water. In fact, a temperature increase of 5 to10 °F (3 to 6 °C) in the United States could result in a decrease in soil moisture of 10 to 30 percent during the summer. A decrease in soil moisture could cause natural vegetation and crops to dry out. This could severely impact the environment as well as the economy Temperature and Water

48. Atmospheric carbon dioxide concentration (ppmv) and temperature change (°C) observed during the past 160 thousand years and predicted during the next 10 thousand years. Historical carbon dioxide data was collected from Antarctic ice cores; temperature changes through time are relative to the present temperature. Graph adapted from the Whitehouse Initiative on Global Climate Change.

49. As concentrations of CO2 in the air decrease, so does the temperature. As concentrations of CO2 in the air increase, so does the temperature. Concentrations of atmospheric CO2 are expected to increase dramatically in the future. Even if emissions of CO2 stay the same as they are now, concentrations of atmospheric CO2 will increase to 700 ppm by 2100emissions (see Remote Sensing: Carbon Dioxide.Remote Sensing: Carbon Dioxide As a result, mean global temperatures will increase by 3.5 °F (1.9 °C) over the next 100 years. CO2 vs Temperature

50. Source: Vimeux, F., K.M. Cuffey, and Jouzel, J., 2002, "New insights into Southern Hemisphere temperature changes from Vostok ice cores using deuterium excess correction", Earth and Planetary Science Letters, 203, 829-843. CO2, CH4 and temperature records from Antarctic ice core data