Ch. 3: Wx Flashcards
Describe characteristics of flow of air around high and low pressure systems?
- High: Inward, Upward, Counterclockwise
- Low: Outward, downward, clockwise
What kind of weather would you expect flying through a low pressure system?
- Rising air
- Cloudiness
- Precipitation
- Bad weather
What kind of weather would you expect flying through a high pressure system?
- Descending air
- Dissipation of clouds
- Good weather
Cold front
- Occurs when a mass of cold, dense, stable air advances and replaces a body of warmer air
- As front passes
- Towering cumulus/cumulonimbus
- +RA accompanied by lightning, thunder, or hail;
- Tornadoes possible.
- During passage,
- Poor visibility
- Winds variable/gusting
- Temp/dew point and pressure drop rapidly
Occluded Front
Fast moving cold front catches up to slow moving warm front
Warm Front
- Boundary area formed when warm air mass contacts and flows over a colder air mass
- As the front passes:
- Stratiform clouds
- Drizzle
- Low ceilings
- Poor visibility
- Variable winds
- Temperature rise
Stationary Front
- Forces of two air masses are relatively equal
- Boundary/front that separates them remains stationary and influences local weather for days.
- Mixture of both warm and cold front
What causes winds aloft to flow parallel to the isobars?
Coriolis Force
Why do surface winds generally flow across the isobars at an angle?
Surface Friction
At what rate does atmospheric pressure decrease with an increase in altitude?
1” Hg per 1,000’
What does dew point mean?
Temp at which air must be cooled to become saturated
What factors must be present for a thunderstorm?
- Sufficient water vapor
- Unstable lapse rate
- Initial upward lifting to start the storm process
Stages of a TS
- Cumulus Stage
- Mature Stage
- Dissipating Stage
Name several types of fog
- Radiation fog
- Advection fog
- Upslope fog
- Frontal fog
- Steam fog
What causes radiation fog?
Ground cools the adjacent air to the dew point on calm, clear nights
What causes advection fog?
- Warm humid air moves in over a cold surface
- Primarily along coastal areas
What causes upslope fog?
- Moist, stable air being cooled adiabatically as it moves up sloping terrain
- Often dense and extends to high altitudes
Where is wind shear likely to occur?
- Low level temperature inversion
- In a frontal zone
- Clear air turbulence at high levels with jet stream
What Wx info can you check to determine if wind shear will affect your flight?
- TAF
- Sigmet/Airmets
- Pireps
- LLWAS
- Metars
- Winds aloft
What pertinent info should a Wx briefing include?
- NOTAMs
- Adverse conditions
- VFR flight not recommended
- Synopsis
- Current conditions
- En route forecast
- Destination forecast
- Winds aloft
- ATC delay
- May obtain on request: SUA, MOAs, MTRs, Warning areas, Alert areas, etc.
HIWAS
- Hazardous Inflight Wx Advisory Service
- Continuous broadcast of inflight wx advisories
- Navaids with HIWAS depicted in sectionals with “H” in upper right corner
What is Flight Information Service (FIS-B)?
- Offered through ADS-B Flight deck display of aviation weather and aeronautical information
- Is not real time Wx info
- Delayed 5-15 minutes
What is a METAR and what are two types?
- Meteorological Aerodrome Report
- Hourly report of surface observations at airport
- Types:
- Routine
- Special
Aviation Area Forecast (FA)
- Specified wx phenomena covering a flight info region
- Used to
- Determine en route forecast
- Interpolate conditions at airport without TAF
- Issued 3 times daily
What are Center Wx Advisories?
- An aviation warning for use by air crews to anticipate and avoid hazardous conditions
- Not a flight planning tool
- Used in flight
- Reflects current conditions
- Valid 2 hours
What is a Surface Analysis Chart?
- This is the current weather map
- Not a forecast
- Current surface observations
- Depicts:
- Highs and lows
- Ridges and troughs
- Location and character of fronts
- Isobars