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PRACTICE QUIZ PARTS 1 & 2 Open Wednesday 16 Sept!

Cameron Clough – I have your clicker!. PRACTICE QUIZ PARTS 1 & 2 Open Wednesday 16 Sept!. Be sure to try BOTH PARTS of the practice quiz in VISTA! Go to either “Quizzes” from the homepage OR “Assessments” on the left panel. Opens Sept 16 th at 1 pm, and will remain open until October 21 st.

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PRACTICE QUIZ PARTS 1 & 2 Open Wednesday 16 Sept!

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  1. Cameron Clough – I have your clicker! PRACTICE QUIZ PARTS 1 & 2 Open Wednesday 16 Sept! Be sure to try BOTH PARTS of the practice quiz in VISTA! Go to either “Quizzes” from the homepageOR “Assessments” on the left panel. Opens Sept 16th at 1 pm, and will remain open until October 21st ALSO, the extra credit survey closes Sept 18th! (link in VISTA)

  2. Earth’s radiation balance: SURFACE SURFACE =114% Input: 47% from the Sun 96% from the atmosphere Total: 143% Output: 109% as IR to the atmosphere 5% as IR to outer space 29% as heat to the atmosphere Total: 143%

  3. Earth’s surface temperature SURFACE Earth’s surface radiates 114% of 342 W/m2 = 390 W/m2 SURFACE TEMPERATURE: 390 W/m2 … Stefan-Boltzmann…  288K (15°C)

  4. Summary: Radiation Balance II • Earth’s mean surface temperature is higher than its effective radiating temperature because of greenhouse gases • Earth’s atmosphere lets most of the incoming, short wavelength, solar radiation through, but absorbs much of the outgoing, long wavelength, infrared radiation emitted by Earth • Latent and sensible heat transfer from Earth’s surface to its atmosphere help keep the surface cooler than it would otherwise be • The radiation budget for Earth’s surface, its atmosphere, and the planet as a whole are typically in balance. Changes in solar constant, albedo, and greenhouse gases can all perturb the system, leading to a new equilibrium temperature. Relevance: Earth’s habitability, greenhouse warming

  5. Clicker Q: Evaporation of water (latent heat transfer), increases the water vapour content in the atmosphere. With increased water vapour content, what happens to the DENSITY of air? • Air density INCREASES • Air density DECREASES • Air density DOES NOT CHANGE

  6. Atmosphere I: General atmospheric circulation Goals for Today • CONTRAST the equator-to-pole temperature gradient with and without atmospheric circulation • DEVELOP the general atmospheric circulation starting with the distribution of incoming solar energy • PREDICT, for any latitude, the direction from which surface winds blow, based on the general atmospheric circulation

  7. To achieve these goals, you’ll need to… • Explain how Earth’s curvature and rotation produce… • …unequal distribution of incoming and outgoing energy • …the CORIOLIS EFFECT • Describe why air temperature and moisture content influence VERTICAL motion in the atmosphere • e.g. Warm, wet air rises; cool, dry air sinks • Use continuity to reconcile these vertical motions with global circulation • e.g. Air rising away from Earth’s surface must be replaced • Synthesize all concepts to develop circulation patterns for any planetary scenario

  8. RELEVANCE Climate Weather Energy

  9. Clicker question: Which of the following locations receives the MOST energy per square metre on December 21st at midday?Please answer INDIVIDUALLY (w/o discussion) • 90⁰N (the North Pole) • 23⁰N (tropic of Cancer) • 0⁰ (the equator) • 23⁰S (tropic of Capricorn) • 90⁰S (the South Pole)

  10. Incoming energy distribution: Curvature Marshak, Fig 20.10

  11. Clicker question: Which of the following locations receives the MOST energy per square metre on March 21st at midday? • 90⁰N (the North Pole) • 23⁰N (tropic of Cancer) • 0⁰ (the equator) • 23⁰S (tropic of Capricorn) • 90⁰S (the South Pole)

  12. Incoming/Outgoing energy distribution Top of Atmosphere SURPLUS Energy DEFICIT DEFICIT Outgoing Radiation Absorbed at Surface 90°N 0° 90°S Latitude (after Gill, Figure 1.1)

  13. Temperature, moisture, and air density T  air density  air rises Common molecules in air N2 : MW = 28 O2 : MW = 32 H2O : MW = 18 evaporation  water vapour (H2O)  H2O displaces heavier molecules  air density  air rises

  14. Non-rotating Earth. No continents. Sinking air.Cold & dry equator Rising air.Heat & H2O vapor Sinking air.Cold & dry

  15. Non-rotating Earth. No continents. Clicker question: FROM what direction do the surface winds blow for the sailboat? FROM the… Surfacewind? equator • north • northwest • northeast • south • southeast

  16. Non-rotating Earth. No continents. Sinking air.Cold & dry Surfacewind equator Rising air.Heat & H2O vapor Surfacewind Sinking air.Cold & dry

  17. Non-rotating Earth. No continents. Hadley Cell Hadley Cell Marshak, Figure 20.11a

  18. Rotating Earth. No continents. PolarCells 90º FerrellCells 60º 30º HadleyCells 0º 30º FerrellCells 60º PolarCells 90º

  19. Rotating Earth. No continents. H Dry Precipitation L Atmosphericpressure Rainy H Dry L Rainy H Dry Rainy L H Dry Marshak, Figure 20.11c

  20. Coriolis Effect Objects in MOTION, on a ROTATINGframe of reference, tend to followCURVED PATHS. 0 m/s (0 km/hr) Eastwardvelocities 90º ~300 m/s (~1080 km/hr) 49º ~444 m/s (~1600 km/hr) 0º

  21. Objects in MOTION, on a ROTATINGframe of reference, tend to followCURVED PATHS. Coriolis Effect Eastward velocity ~348 m/s New York City (41ºN x 74ºW) Equator Bogota (4.5ºN x 74ºW) Eastward velocity ~444 m/s

  22. Objects in MOTION, on a ROTATINGframe of reference, tend to followCURVED PATHS. Coriolis Effect Northern Hemisphere: TO THE RIGHT Southern Hemisphere: TO THE LEFT

  23. Coriolis Effect REMEMBER: Northern Hemisphere: TO THE RIGHT! Southern Hemisphere: TO THE LEFT! …or go one better…be able to RECONSTRUCT this information from your knowledge...(1) this planet is spherical (approximately) and (2) the Sun rises in the east and sets in the west…

  24. Rotating Earth. No continents. Clicker question: 90º FROM what direction do the surface winds blow for the sailboat? FROM the… 60º 30º 0º • north • south • northeast • southwest • southeast 30º 60º 90º

  25. Rotating Earth. No continents. One more clicker question: 90º FROM what direction do the surface winds blow for the sailboat? FROM the… 60º 30º 0º • north • south • northeast • southwest • southeast 30º 60º 90º

  26. Rotating Earth. No continents. 90º Polar easterlies Westerlies 60º 30º Northeast Trades 0º Southeast Trades 30º 60º Westerlies Polar easterlies 90º

  27. Coriolis Effect: last point MAXIMUM at poles Large difference in circumference between these latitudes increasing Not much difference in circumference between these latitudes ZERO at ZERO (the equator) increasing MAXIMUM at poles

  28. Heat transport: redistribution

  29. Rotating Earth WITH continents.

  30. Summary: General Atmospheric Circulation • Different latitudes receive and emit different amounts of energy due to Earth’s curvature & heat transfer processes • Hot, wet air rises. Cold, dry air sinks. • Objects in motion on this rotating planet tend to follow curved paths (Coriolis effect: to the RIGHT in the N. Hem. & to the LEFT in the S. Hem.) • Differential heating, air rising and sinking, the Earth rotating, all lead to the general atmospheric circulation (which you can develop) Relevance: weather, climate, energy

  31. Slides not used below.

  32. Clicker question **alternate**: During summer in Vancouver… • the equator gets the most solar radiation • the Arctic gets the most solar radiation • the Earth is close to the Sun, compared to during winter in Vancouver • the northern hemisphere is tilted toward the Sun • the southern hemisphere is tilted toward the Sun

  33. Coriolis Effect What about east-west? Hgravity For objects at rest, Hg = Hc Fcentrifugal Hcentrifugal Fgravity For objects heading EASTWARD (FASTER than rotation), Hg < Hc object pulled SOUTHWARD (to the RIGHT!) Fcentrifugal For objects heading WESTWARD (SLOWER than rotation), Hg > Hc object pulled NORTHWARD (to the RIGHT!) Fcentrifugal (in the Northern Hemisphere)

  34. Coriolis Effect Here’s the math! C = (2WsinF) v m • C = Coriolis “force” • W = angular velocity of the Earth (in radians/time) 360º/24 hours = 2p radians/24 hrs = 7.29 x 10-5 sec-1 (Wis a constant) • = latitudev = velocitym = mass

  35. Coriolis Effect What’s the point of the math? C = (2WsinF) v m 1. Coriolis increases with increasing latitude C = 0 at the equator! C is maximum at the poles. 2. The faster you go, the stronger the Coriolis! 3. The more massive you are, the stronger the Coriolis! True for any object in motion on a rotating frame of reference e.g. air, water…

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