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Climate October 22, 2012

Climate October 22, 2012. Lecture learning objectives:. You should be able to: Describe the difference between climate and weather Describe major climate factors -radiation , albedo, energy budgets , wind and atmospheric circulation, temperature , and moisture.

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Climate October 22, 2012

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  1. ClimateOctober 22, 2012

  2. Lecture learning objectives: You should be able to: • Describe the difference between climate and weather • Describe major climate factors • -radiation, albedo, energy budgets, wind and atmospheric circulation, temperature, and moisture. • Explain the differences between urban and forest microclimates and what drives those differences. • Identify indicators of climate change

  3. Micro, meso, macro and megaclimate Scale Length Area Locale Micro 1 m - 1 km 1m² - 1 km² local Meso 1 - 100 km 1 - 100 km² regional Macro 100 - 10 000 km 100 - 10 000 km² continental Mega >10 000 km >10 000 km² global

  4. What is the difference between weather and climate? • Climate is what you expect • Weather is what you get

  5. Climate factors • Radiation and albedo • Energy budgets • Wind – global circulation, high and low pressure systems • Temperature – effects of latitude and elevation, greenhouse effect • Moisture – types of precipitation, seasonal distribution, latitudinal distribution, orographic precipitation

  6. Ecosystems use solar energy todrive processes • < 2 % of solar energy is used for photosynthesis • Most goes into evaporating water. • Heat balance, hydrologic cycle and climate are strongly linked. • Forests have 70% of leaf area on the Earth.

  7. Radiation and albedo • Forms of radiation Ultraviolet, visible, infrared (heat) short wave long wave http://serc.carleton.edu/images/eslabs/weather/balance_diagram_simple.jpg

  8. www.windows.ucar.edu/earth/Atmosphere/images/...

  9. AlbedoProportion of shortwave radiation that is reflected (0-1 scale) Albedos of different surfaces Vegetation type Albedo Temperate forest (summer) 0.12 (winter) 0.25 Tropical forest 0.07 Savanna 0.16 Field, grassland 0.16 (summer) Desert 0.35 Ocean ice 0.5-0.7 Asphalt 0.04-.12 Color of the surface is important – white surfaces have the highest albedos – dark surfaces (black) have the lowest albedos

  10. Species have different leaf strategieswith respect to radiation • Species adjust leaf areas to capture light or handle heat loads. • western hemlock (shade tolerant) has greater leaf area (m2 leaf/m2 of surface) than Douglas-fir (shade intolerant). • Species like Noble fir have sun and shade needles. • Eucalyptus leaves are vertical to reduce heat load in a hot environment. http://www.nps.gov/neri/naturescience/images/web_HWA_01.jpg http://t1.gstatic.com/images?q=tbn:ANd9GcRcUJDJPOFyMWtGLbA-DNCe0QgQX7IC4Hw-mnLvdigIDHtZDFCUAxYAyNafZQ http://www.cirrusimage.com/Trees/Eucalyptus_leaves.jpg

  11. Global wind and circulation patterns Broadly predicts global to continental climate Nasa.gov

  12. Local winds

  13. Santa Ana Winds USA Today

  14. Mountain valley winds http://t3.gstatic.com/images?q=tbn:ANd9GcTRZqSuMV9Rkd9MIIk-FqKXpexuhgPVn8Fiy0O1arw0od_gmz2rP778sCCH

  15. Urban canyons (valleys) Urban structure also affects winds, albedo and radiation http://en.wikipedia.org/wiki/File:42nd_st_canyon.jpg

  16. TEMPERATURE INVERSIONS Ag.arizona.edu apollo.lsc.vsc.edu http://www.stuffintheair.com/images/Inversion_Smoke.jpg

  17. Temperature Global temperatures are highest in tropics and lowest at the poles Lowest at highest elevation

  18. Temperature at noon on field trip Oct 13, 2012 46 F Stampede Pass 3965 feet 64 F Ellensburg 1764 feet 58 F Seattle 100 feet

  19. Moisture – humidity and precipitation Precipitation tends to be highest in tropics and lowest at the poles Modified by mountain ranges that produce orographic rainfall on the windward side of mountains and rain shadows on the lee side of mountains http://www.whymap.org/whymap/EN/Downloads/Additional_global_maps/precipitation_g.jpg?__blob=normal&v=3

  20. 3. Urban and Forest Microclimates • Forest and urban trees modify the climate because of albedo and energy budgets. • Trees cool the environment (low albedo, high evapotranspiration, low sensible heat) • Concrete and dark asphalt surfaces heat the environment (high albedo, no transpiration, low evaporation, high sensible heat. The urban heat island effect

  21. Clearcuts are hotter and colder than forests. South slopes, particularly SW slopes are hotter and drier than north slopes. Steeper slopes are hotter.

  22. www.arch.hku.hk

  23. Mitigation of Urban Heat Islands • Increase vegetative cover • Use porous concrete surfaces • Change the albedo of surfaces

  24. Pacific Ocean to the westMountain ranges that block and deflect PNW weather and climate are dominated by two elements:

  25. Average Rain Per Year • Seattle: 37” • New York City: 47” • Miami: 56” Number of Cloudy Days Per Year Seattle: 228 (61%) Houston: 166 Miami: 117 (31%)

  26. East vs West Cascades • Annual temperature range • East side: varies by 60ºF between Jan-July • West side: varies by 30ºF • Precipitation range • I-84 along Columbia River gorge: Rain forest near Cascade Locks (80”/year) to arid environment near The Dalles (13”/year) in just 45 miles

  27. Most temperate forests are dominated by broad-leaved deciduous trees • If enough water to support trees vs grasses • Dormant during winter • New leaves in spring • Photosynthesis in wet summer

  28. PNW EcosystemsWhy do conifers dominate here? • Short, cool summers • Mild winters • Precipitation mostly in winter (75% between Oct-Mar) • Dry summers

  29. Photosynthesis and Water Conservation are opposites. The Photosynthesis-Transpiration Compromise: must open stomata to bring in CO2 but in so doing, the plant loses water vapor

  30. The PNW west-side Challenge • Optimum photosynthesis: warm and bright • PNW is warm and bright mid-July to mid-Sept • * These are the driest months * • Regulate stomatal opening to reduce water loss during drought conditions • Lose best opportunity for photosynthesis

  31. Solution? Retain leaves and do photosynthesis whenever possible

  32. West  East • Precipitation drops off rapidly east of the passes • Drought-tolerant pines and junipers • Grassland and desert

  33. Global Climate Change • Thin layer of atmosphere traps some of the Sun’s energy and heat • Problem = Thickening layer (“Greenhouse gases”) • Average global temperatures are rising

  34. Instrument Data (thermometer records) Global mean surface temperature anomaly 1850 to 2006 relative to 1961–1990

  35. Hotter than normal globally • Hottest years on record in USA: 1934, 1998, and 2006 • Red=warmer than average • 1934: hot in some areas; 1998 & 2006: globally hotter

  36. Departure from normal temperatures Image credit: U.S. Global Change Research Program (www.globalchange.gov).

  37. Past warming trends • From 1000-2000: 3 little blips (3 between 1000-1400 A.D.) before current trend • Shorter duration and smaller magnitude

  38. Indications of Global Climate Change 1. Glaciers are melting 2. Heat waves 3. Ocean temperature is rising 4. More powerful storms 5. Increased flooding 6. Drought (relocalization of precipitation) 7. Melting ice caps 8. Melting tundra 9. Tropical plants moving north 10. Insect infestations 11. Sea level is rising And more

  39. 1. Glaciers are melting 1928 2004 Upsala Glacier in South American Andes in Argentina - Retreating 180 feet per year

  40. The total surface area of glaciers worldwide has decreased by 50% since the end of the 19th century

  41. What controls glacier changes? Accumulation (snowfall, rainfall) Temperature (summer/winter) Dr. Michelle Koutnik (UW PhD ‘07)

  42. 2. Heat waves • Heat wave in Europe 2003- killed 35,000 • Record-breaking heat in 2005 in many American cities • Hottest and longest duration above 100F • Of the 21 hottest years on record (global), 20 within last 25 years

  43. 3. Ocean temperature is rising • Cannot get the long history of temperature data • Warming trend • Since 1960’s, more warm temperature anomalies

  44. 4. More powerful storms • Increased frequency • 2004: Japan’s typhoons (10) • U.S. severe hurricanes (Katrina) • 2005: First time World Meteorological Society ran out of names (27)

  45. 4. More powerful storms (cont.) • Unusual places • 2004: first hurricane in Brazil • Previously thought impossible in South Atlantic

  46. Power of hurricanes correlates with sea surface temperature

  47. 5. Increased flooding Number of Major Flood Events Source: Millennium Ecosystem Assessment

  48. 6. Relocalization of precipitation • Global precipitation increased by 20% in last century • But not evenly distributed • Severe droughts

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