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SOAR 2007

SOAR 2007. Energy and Temperature. Energy & Temperature. Insolation Spectrum Distribution with latitude Distribution with albedo Interaction with Air, Land & Water Reflected Absorbed by atmosphere Absorbed by land Absorbed by water Effect of insolation Heating & temperature.

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SOAR 2007

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  1. SOAR 2007 Energy and Temperature

  2. Energy & Temperature • Insolation • Spectrum • Distribution with latitude • Distribution with albedo • Interaction with Air, Land & Water • Reflected • Absorbed by atmosphere • Absorbed by land • Absorbed by water • Effect of insolation • Heating & temperature

  3. Temperature Scales (Again!) • Celsius • 0 - fresh water freezes • 100 - fresh water boils at 1013.2 hPa (1 atm) • Kelvin • Based on gases • TC + 273 = TK • Fahrenheit – used only in US • 0 ~ salt water freezes • 100 ~ human body temp. • TC = (5/9)(TF - 32) • TF = (9/5)TC + 32) Plots for different gases meet at -273 C Pressure -273 Temperature C Celsius – Fahrenheit touch points: -40 C = -40 F 16 C = 61 F 28 C = 82 F

  4. Temperature Scales “At 40 below it doesn’t matter!” Celsius – Fahrenheit touch points: 28C ≈ 82F 16C≈61F -40C = -40F

  5. Atmospheric “Windows” • Solar Radiation • air transparent to some (visible, radio, some IR) • opaque to others (some IR & UV, all X- & -rays)

  6. Solar Radiation & Latitude • Latitude • Latitudes close to equator get more annual sun • Tropics • 23.5 N - Tropic of Cancer • 23.5 S - Tropic of Capricorn • Polar Regions • 66.5 N – Arctic Circle • 66.5 S – Antarctic Circle Sun directly overhead on solstice Sun does not set (or rise) on solstice

  7. Sun Angle & Latitude At the Equator, the noontime sun goes from 23.5 South of the zenith to 23.5 North of the zenith. All days have 12 hours of daylight. Directly Overhead Southern Horizon At the Tropic of Cancer, the noontime sun is directly overhead on the northern summer solstice. In Canton, the noontime sun goes from 45-23.5= 21.5 above the horizon to 45-23.5= 68.5 above the horizon. • Insolation depends on sun angle. At the Arctic Circle, the sun goes from being just at the horizon on the winter solstice to 47 above the horizon. Equator No-shadow days! Tropic of Cancer Canton Highest angle changes by 47° from 21.5° to 68.5° Point of sunrise & sunset changes by 68° From azimuth 56° to 124° (90° is east) Arctic Circle

  8. Insolation in Canton • Summer sun 21.5 ~700 W/m2 from sun reaches surface ~260W falls on one m2 in Canton in winter ~500W falls on one m2 in Canton in spring & fall ~665W falls on one m2 in Canton in summer

  9. Insolation & Latitude

  10. Insolation & Latitude • Tropics • energy surplus • Poles • energy deficit • Energy must be transported to poles

  11. Latitude & Temperature • Temperature plots of data from worldclimate.com

  12. Reflected Radiation -- Albedo • Different surfaces reflect differently Melting ice & snow increases absorption, enhances heating Melting sea ice increases absorption, enhances heating “Ice-Albedo Effect”

  13. Insolation on Earth’s Surface • Distributed by latitude & vegitation Deserts get > 200 W/m2 Rainforests get less due to clouds

  14. Insolation • Short wave radiation • visible light • emitted by Sol (the sun) • absorbed by land & water • not absorbed by air • Long wave radiation • infrared (IR) • emitted by Earth • absorbed by air, land & water shortwave longwave

  15. Simplified Energy Budget Shortwave radiation from sun (light) absorbed by Earth (land & water) Earth heats & emits longwave radiation Top of the atmosphere receives 1372 W/m2 - solar constant 10 W = power to lift 1 kg 1 meter in 1 second

  16. Energy Budget • Insolation – incoming solar radiation • reflected & absorbed ~30% reflected shortwave

  17. Energy Budget • Insolation – incoming solar radiation • reflected & absorbed ~30% reflected Outgoing shortwave reflected from clouds and deserts, absorbed by ocean & forests

  18. Energy Budget • Insolation – incoming solar radiation • reflected & absorbed ~70% re-radiated ~30% reflected ~19% absorbed by air & clouds shortwave longwave ~51% absorbed by surface

  19. Energy Budget • Insolation – incoming solar radiation • reflected & absorbed ~70% re-radiated Outgoing longwave radiated by surfaces ~51% absorbed by surface

  20. Energy Budget • Insolation • Sun’s incident energy drives air motions (energy from deep interior adds a tiny bit) • Distribution of Sunlight • Reflection from clouds, landscape • Absorption by atmosphere • Absorption by surface • Albedo = ratio of sunlight reflected • Earth: 0.367 • Moon: 0.113 • Mars: 0.15 • Venus: 0.84

  21. Energy Distribution • Convection – hot stuff moves • Conduction – hot stuff heats neighbors • Radiation – heat moves as IR radiation

  22. Insolation: 1,373 W/m2 Most solar energy comes in as light (shortwave radiation) 30% Reflected by atmosphere & surface 20% Absorbed by atmosphere 50% Absorbed by Earth’s surface

  23. Insolation: 1,373 W/m2 Most solar energy comes in as light (shortwave radiation) Reflection of sunlight 30% Reflected by atmosphere & surface Air Clouds 20% Absorbed by atmosphere Surface 50% Absorbed by Earth’s surface

  24. Energy Emitted by Planet Earth % of total insolation Thermal Equilibrium 30% reflected directly to space 70% emitted as IR

  25. Energy Flow from Surface 7% conducted to air 23% transferred by water 20% radiated as IR (longwave) ~ 50% of total insolation absorbed by surface

  26. Energy Absorbed by Atmosphere % of total insolation 20% from Sun 7% conducted from surface 23% transferred by water 8% radiated by surface

  27. Energy Absorbed by Atmosphere % of total insolation 20% from Sun 7% conducted from surface 23% transferred by water 8% radiated by surface

  28. Urban Heat Islands • Structures and pollution increase heat

  29. Urban Heat Islands • May be giving false increases in global temperature since most weather stations are at airports in urban areas!

  30. Energy Absorbed by Atmosphere % of total insolation 20% from Sun 7% conducted from surface 23% transferred by water 8% radiated by surface

  31. Energy Transfer by Water Evaporating water absorbs energy from water, cooling it. Condensing water releases energy to air, heating it. • Latent heat effects weather

  32. Energy Absorbed by Atmosphere % of total insolation 20% from Sun 7% conducted from surface 23% transferred by water 8% radiated by surface

  33. Moist air rising  stormy Dry air falling  Arid Moist air rising  stormy Dry air falling  Arid Moist air rising  stormy Polar High Easterlies Polar Front Westerlies STHPC NE Trades Hadley Cells ITCZ SE Trades STHPC Westerlies Polar Front Easterlies Polar High

  34. Atmospheric Circulaton • Ground conducts heat to adjacent air • Heated air rises • Troposphere cools with altitude • Environmental lapse rate Inversion = warmer air aloft

  35. Energy Absorbed by Atmosphere % of total insolation 20% from Sun 7% conducted from surface 23% transferred by water 8% radiated by surface

  36. Greenhouse Effect • Light from sun gets absorbed by Earth • Earth radiates infrared

  37. Greenhouse Effect • Light from sun gets absorbed by Earth • Earth radiates infrared Earth re-emits energy absorbed from sunlight as infrared infrared

  38. Greenhouse Effect • IR gets absorbed by atmosphere  Air heats  Air absorbs more water  Moist air absorbs more IR & heats more  absorbs more water

  39. Global Warming Increasing greenhouse gases decreases longwave (IR) radiation lost to space Increasing greenhouse gases increases absorption of longwave (IR) radiation by ground Atmosphere Warms!

  40. Venus: Greenhouse gone wild! The difference between Earth and Venus!

  41. Complete Energy Budget

  42. Sunlight & Temperature • Noon not warmest time of day • Solstice not warmest time of year • Temperature waits for surface to heat air!

  43. Insolation on Land and Water • Land • Light heats surface, some downward conduction • no downward transmission or convection • Conduction to subsurface very slow • Water • Surface molecules evaporate, cooling surface • Light penetrates to depths, heats subsurface • Heats slowly due to high specific heat • Convection moves heat across surface and beneath surface … currents

  44. Land and Water • Water distributed heat more than land

  45. Energy Absorbed by Water • Specific Heat • Energy absorbed/released to change temp. • Latent Heat • Energy needed to change phase (substance remains at same temperature)

  46. Energy Absorbed by Water • Specific Heat • Energy absorbed or released to change temp. Raising 1 kg of water 1°C absorbs 4,168 Joules 10 cm square cube of water Huge! 1 kg 4000 Joules ≈ energy to lift 400 kg or 900 lb 1 m

  47. Energy Absorbed by Water • Latent Heat • Energy absorbed or released to change phase Evaporating 1 kg of water absorbs 2,257,000Joules Even Huger! 10 cm square cube of water 1 kg 2,257,000 Joules ≈ energy to lift 225,700 kg or 507,000 lb 1 m

  48. Land and Water • Maritime climates milder than continental Seattle, 48 N, maritime Minot, ND, 48 N, continental Monthly average temperature varies by 14 C in Seattle, 35 C in Minot

  49. Atmospheric Water & Warming • Clouds & Rain • clouds reflect sunlight, shade ground • so cloudy places should be cool … • moist air absorbs more IR than dry • so humid places should stay warm … Monsoon rains cool Lhasa and Calcutta. Lhasa, Tibet Calcutta, India

  50. Atmospheric Water & Warming • More evaporation • more clouds • surface shaded • surface cools • atmosphere cools Negative feedback prevents runaway warming

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