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Private Pilot Ground School モドキ

L. WEATHER THEORY

      • Cause of weather
        • Every physical process of weather is caused by UNEQUAL HEAT EXCHANGE.
        • Unequal heat exchange = Convection = Pressure Difference. It causes
          • air to flow, wind to blow
          • moisture to added and moves to form a cloud and fogs
          • to create rain or ice in the air
          • thunderstorms, windshear, low visibility, and other weather hazard.
        • Unequal heat exchange causes variation in altimeter setting (by pressure difference)
    1. CORIOLIS FORCE
      • deflects the wind (flow of fluid) to the right in the northern hemisphere.
      • makes wind to blow parallel, instead of perpendicular, to isobar
      • Less Coriolis force bear surface due to friction with ground
    2. Humidity
      • It determines general weather.
      • Moisture is added to air.
      • Relative humidity
        • Amount of Moisture compare to Maximum Moisture that air can hold
        • Amount of moisture can be held is affected by temperature.
      • Dewpoint (temp that air became 100% saturated. visible moisture)
    3. CLOUD
      1. Families of cloud
        • Low cloud Surface to 6,500 ft.
        • Middle cloud 6,500ft. - 20,000ft. (Alto-)
        • High cloud above 20,000ft. (Cirro-)
        • Extensive vertical development cloud
      2. Rain Cloud (nimbo-)
      3. Towering cumulus cloud
        • Cumulonimbus cloud
      4. Form of cloud
        • Straus: Stable Airmass, Less wind ,fog, continuous precipitation
        • Cumulus: Un-Stable Airmass, Gust, turbulence, showery precipitation
      5. Lenticular Cloud
    4. Thunderstorm
      1. Hazards
        • Turbulence: Substantial or Fatal structure damage, loss of control.
        • Lighting: Temporally loss of vision, electric failure,
        • Hail: Structure damage,
      2. Lifecycle
        1. cumulus stage: Up draft
        2. Mature stage: Most dangerous
          • Rain begins at Surface
          • Lighting
          • Severe and destructive Up and down draft
        3. Dissipating stage: Down draft, Weakening, but it energy may be transferring to next thunderstorm
      3. Squall line = Line of thunderstorm
      4. Embedded thunderstorm = hidden
    5. Wind shear (TURBULENCE)
      • It is sudden change in wind velocity or direction
        • horizontally or vertically.
      1. Where does it occur?
        1. Near thunderstorm,
        2. close to ground with strong wind.
        3. Strong Temperature Inversion
      2. Loss of control
      3. Loss of lift (because of airspeed change) = stall or high descent rate = may crash into ground
      4. Loss of altitude
    6. Temperature Inversion
      • Temperature increases as altitude increase,
      • Very Stable Airmass, such as Clear still night
      • Warm airmass is moving over cold airmass.
    7. Mountain wave
      • Near mountain top, wind blowing across a ridge
      • Lenticular Cloud
      • Very strong wind and turbulence, even it seems stationary or invisible.
    8. STABILITY of AIRMASS
      Type Stable Airmass

      Unstable Airmass

      Lapse Rate Low High
      Air Smooth Turbulent
      Cloud Stratiform Cumuliform
      Precipitation Continuous Showery
      Visibility Low, Fog, Haze Good clear (except rain)
    9. Icing
      1. Structural Icing
        • Raining below freezing temperature
        • Supercooled Water (Liquid State even below freezing)
        • Type of Icing
          1. Clear
            • Hard and Clear, Heavy,
            • often Cumulus Type Cloud
            • large water droplets, slow freezing
            • Adheres and hard to remove
            • changes shape of airfoil
          2. Rime
            • Small water droplets with air trapped
            • somewhat rough-looking appearance and a milky-white color.
            • often stratus type cloud
          3. Mixed (Mixture of Clear and Rime)
        • Supercooled Water will freeze at impact
      2. Carb Icing is likely to occur when
        • temperature 20 to 70
        • humidity more than 50%, more likely to happen above 80%
      3. review several accident reports if time is available
    10. Frost on wing
      1. It causes early separation of air.
      2. Difficult or Impossible to take off.
    11. Front
      1. Cold front
        • Colder Air overtakes Warmer Air
        • Steep slope and Narrower
        • Cumulus Type Clouds, and chance of Thunderstorm with faster moving cold front
      2. Warm front
        • Warmer air move over cold airmass
        • Shallow Slope
        • Stratus Type Cloud for wide area
        • Occasional Cumulonimbus Clouds = Embedded thunderstorm
        • Higher chances of Freezing Rain
      3. Stationary front
        • no or very few move
        • warm and cold air flows parallel but opposite direction
        • same pressure
        • weather lasts extended time
      4. Occluded front
        • Cold front passes warm front
        • complex
        • Widespread, poor visibility, possible icing
      5. Cold Air = More Dense = Moves Faster
    12. Fog
      1. Condition
        • High Humidity
        • Few temperature dewpoint spread
        • needs condensation nuclei (particles so that moisture can condense around it)
      2. Radiation fog
        • Clear, calm night
        • Land area
      3. Advection fog
        • Warm, Moist Air flows over Cold Land (Area)
        • large temperature difference
        • Shore line to cold Land area
      4. Upslope fog
        • Moist Air flow up a slope, and cooled
      5. Steam fog
        • cold air moves over water
        • turbulence
      6. Rain-Induced Fog
      7. Fog and Mist
        • Fog = Visibility Less than 5/8 Statute Mile
        • Mist = BR = Fog reduces visibility to between 5/8 SM to 6 SM.
      8. Haze, Smoke, Smog
        1. Haze
          • fine dust or salt in the air
          • restricted visibility
          • stable air
        2. Smoke
          • industrial area, or fire
        3. Smog
          • Mixture of smoke and fog
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