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Weather 101 and beyond

Learn about the boundary layer, surface winds, surface roughness, air pressure variations, temperature lapse rates, energy transport, atmospheric motion, and numerical weather prediction.

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Weather 101 and beyond

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  1. Weather 101 and beyond Edward J. Hopkins Dept. of Atmospheric & Oceanic Sciences Univ. of Wisconsin-Madison Midwest Hot Air Balloon Safety Seminar “Hot Aireventure” Oshkosh 3 March 2001

  2. Boundary Layer • Where we live • Extends from surface to ?

  3. Concerns of Balloonists • The Winds • The Surface

  4. WIND • Why Winds? • Local Thermal Effects • Large Scale Dynamic Effects

  5. High Pressure Systems • Circulation • Consequences • Types

  6. The Surface • The “Obvious” • Obstacles to take-off and landing (e.g., trees, power lines, animals) • The Surface and the Winds • Affects the Boundary Layer wind flow • Can produce local wind regimes

  7. Relative Surface Roughness

  8. Quiz • Which way do winds blow around: High Low

  9. Features in a Surface Low (Convergence & Ascent)

  10. Features in a Surface High(Sinking & Divergence)

  11. January Temperatures - Madison, WI (1981-90) Nighttime Daylight Nighttime

  12. January Wind Speeds - Madison, WI (1981-90) Nighttime Daylight Nighttime

  13. July Temperatures - Madison, WI (1981-90) Daylight Nighttime Nighttime

  14. July Wind Speeds - Madison, WI (1981-90) Daylight Nighttime Nighttime

  15. Daily Heating Heat Gain Heat Loss Daylight Nighttime

  16. U.S. STANDARD ATMOSPHERESee Fig. 1.9 Moran & Morgan (1997) Thermosphere Mesopause Mesosphere Stratopause Stratosphere Tropopause Troposphere

  17. Weather Satellites and the Space Science & Engineering Center

  18. BASIC CONCEPTS Air Pressure (con’t.)

  19. Low Pressure High Pressure Explaining Differences in Air Pressure

  20. Display of Pressure Differences on a Weather Map - Isobars

  21. AIR PRESSURE CLIMATOLOGY (con’t.)

  22. AIR PRESSURE CLIMATOLOGY (con’t.)

  23. AIR PRESSURE CLIMATOLOGY (con’t.) 50% of surface

  24. D. VARIATION OF OBSERVED AIR TEMPERATURE WITH HEIGHT • Temperature lapse rates • Rate of cooling with height • Units: degrees per meter or feet or kilometers • Layer nomenclature • lapse • inversion • isothermal where ...

  25. LAPSE CONDITIONSTemperature decreases with height

  26. INVERSION CONDITIONSTemperature increases with height

  27. ISOTHERMAL CONDITIONSTemperature remains constant with height

  28. ENERGY TRANSPORT: CONVECTION (con’t.)

  29. UNSTABLE CONDITIONSCompare Environment with DALRWarmer parcel continues upward

  30. BEAUFORT WIND FORCE SCALE[Modern version, Source: Federal Meteorological Handbook I]

  31. BEAUFORT WIND FORCE SCALE(con’t.)

  32. ASOS Wind InstrumentsWind Vane (left) & Cup Anemometer (right)

  33. Aerovane Measures wind speed & direction

  34. B. EXPLANATIONS of ATMOSPHERIC MOTION • Practical Problems • Historical Concepts • Forces of Motion & Newton's Laws

  35. C. DESCRIBING ATMOSPHERIC MOTION • Reasons for Atmospheric Motions: • Buoyancy Effects or Dynamic Effects

  36. C. DESCRIBING ATMOSPHERIC MOTION • Complications involved with Atmospheric Motion: • Spherical planet; • Rotating planet & non-inertial frame of reference.

  37. DESCRIBING ATMOSPHERIC MOTION(con’t.) • Three-Dimensional Equation of Motion for the Atmosphere • A vector equation; • Entails specification of all forces per unit mass (i.e., equivalent to acceleration); • All forces do not act alone; • Vector sum of individual forces equals net force.

  38. Numerical Weather Prediction

  39. Numerical Weather Prediction

  40. Numerical Weather Prediction

  41. An example of an equation of motionNASA

  42. FORCES ASSOCIATED WITH ATMOSPHERIC MOTION • Following forces influence motion of air parcels: • Pressure Gradient Force • Gravitational Force or Gravity • Coriolis Effect or "Force" • Frictional Force or Friction • Centripetal Forceor more specifically --

  43. PRESSURE GRADIENT FORCE • Generated by differences in pressure within a fluid element; • Responsible for initiation ofall air motion;

  44. PRESSURE GRADIENT FORCE(con’t.) • A 3-dimensional vector that has: • Magnitudeof pressure gradient force vector depends: • directly upon difference in pressure over a given distance (i.e., slope or grade equals “pressure gradient”). • Directionof pressure gradient force vector is: • fromHigh pressure to Low pressure, • along steepest direction of pressure gradient.

  45. PRESSURE GRADIENT FORCE(con’t.)

  46. PRESSURE GRADIENT FORCE(con’t.)

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