Private Pilot Ground School モドキ
L. WEATHER THEORY
- 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)
- 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
- 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)
Form of cloud
- 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
- Rain Cloud (nimbo-)
- Towering cumulus cloud
- Straus: Stable Airmass, Less wind ,fog, continuous precipitation
- Cumulus: Un-Stable Airmass, Gust, turbulence, showery precipitation
Wind shear (TURBULENCE)
- Turbulence: Substantial or Fatal structure damage, loss of control.
- Lighting: Temporally loss of vision, electric failure,
- Hail: Structure damage,
- cumulus stage: Up draft
- Mature stage: Most dangerous
- Rain begins at Surface
- Severe and destructive Up and down draft
- Dissipating stage: Down draft, Weakening, but it energy may be transferring to next thunderstorm
- Squall line = Line of thunderstorm
- Embedded thunderstorm = hidden
- It is sudden change in wind velocity or direction
Where does it occur?
- horizontally or vertically.
Loss of control
Loss of lift (because of airspeed change) = stall or high descent rate = may crash into ground
Loss of altitude
- Near thunderstorm,
- close to ground with strong wind.
- Strong Temperature Inversion
- Temperature increases as altitude increase,
- Very Stable Airmass, such as Clear still night
- Warm airmass is moving over cold airmass.
STABILITY of AIRMASS
- Near mountain top, wind blowing across a ridge
- Lenticular Cloud
- Very strong wind and turbulence, even it seems stationary or invisible.
||Low, Fog, Haze
||Good clear (except rain)
Frost on wing
- Structural Icing
- Raining below freezing temperature
- Supercooled Water (Liquid State even below freezing)
- Type of Icing
- Hard and Clear, Heavy,
- often Cumulus Type Cloud
- large water droplets, slow freezing
- Adheres and hard to remove
- changes shape of airfoil
- Small water droplets with air trapped
- somewhat rough-looking appearance and a milky-white color.
- often stratus type cloud
- Mixed (Mixture of Clear and Rime)
- Supercooled Water will freeze at impact
- Carb Icing is likely to occur when
- temperature 20 to 70
- humidity more than 50%, more likely to happen above 80%
- review several accident reports if time is available
- It causes early separation of air.
- Difficult or Impossible to take off.
- Cold front
- Colder Air overtakes Warmer Air
- Steep slope and Narrower
- Cumulus Type Clouds, and chance of Thunderstorm with faster moving cold front
- 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
- Stationary front
- no or very few move
- warm and cold air flows parallel but opposite direction
- same pressure
- weather lasts extended time
- Occluded front
- Cold front passes warm front
- Widespread, poor visibility, possible icing
- Cold Air = More Dense = Moves Faster
- High Humidity
- Few temperature dewpoint spread
- needs condensation nuclei (particles so that moisture can condense around it)
- Radiation fog
- Clear, calm night
- Land area
- Advection fog
- Warm, Moist Air flows over Cold Land (Area)
- large temperature difference
- Shore line to cold Land area
- Upslope fog
- Moist Air flow up a slope, and cooled
- Steam fog
- cold air moves over water
- Rain-Induced Fog
- Fog and Mist
- Fog = Visibility Less than 5/8 Statute Mile
- Mist = BR = Fog reduces visibility to between 5/8 SM to 6 SM.
- Haze, Smoke, Smog
- fine dust or salt in the air
- restricted visibility
- stable air