Ch. 3: Wx Flashcards
(66 cards)
1
Q
Describe characteristics of flow of air around high and low pressure systems?
A
- High: Inward, Upward, Counterclockwise
- Low: Outward, downward, clockwise
2
Q
What kind of weather would you expect flying through a low pressure system?
A
- Rising air
- Cloudiness
- Precipitation
- Bad weather
3
Q
What kind of weather would you expect flying through a high pressure system?
A
- Descending air
- Dissipation of clouds
- Good weather
4
Q
Cold front
A
- 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
5
Q
Occluded Front
A
Fast moving cold front catches up to slow moving warm front
6
Q
Warm Front
A
- 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
7
Q
Stationary Front
A
- 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
8
Q
What causes winds aloft to flow parallel to the isobars?
A
Coriolis Force
9
Q
Why do surface winds generally flow across the isobars at an angle?
A
Surface Friction
10
Q
At what rate does atmospheric pressure decrease with an increase in altitude?
A
1” Hg per 1,000’
11
Q
What does dew point mean?
A
Temp at which air must be cooled to become saturated
12
Q
What factors must be present for a thunderstorm?
A
- Sufficient water vapor
- Unstable lapse rate
- Initial upward lifting to start the storm process
13
Q
Stages of a TS
A
- Cumulus Stage
- Mature Stage
- Dissipating Stage
14
Q
Name several types of fog
A
- Radiation fog
- Advection fog
- Upslope fog
- Frontal fog
- Steam fog
15
Q
What causes radiation fog?
A
Ground cools the adjacent air to the dew point on calm, clear nights
16
Q
What causes advection fog?
A
- Warm humid air moves in over a cold surface
- Primarily along coastal areas
17
Q
What causes upslope fog?
A
- Moist, stable air being cooled adiabatically as it moves up sloping terrain
- Often dense and extends to high altitudes
18
Q
Where is wind shear likely to occur?
A
- Low level temperature inversion
- In a frontal zone
- Clear air turbulence at high levels with jet stream
19
Q
What Wx info can you check to determine if wind shear will affect your flight?
A
- TAF
- Sigmet/Airmets
- Pireps
- LLWAS
- Metars
- Winds aloft
20
Q
What pertinent info should a Wx briefing include?
A
- 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.
21
Q
HIWAS
A
- Hazardous Inflight Wx Advisory Service
- Continuous broadcast of inflight wx advisories
- Navaids with HIWAS depicted in sectionals with “H” in upper right corner
22
Q
What is Flight Information Service (FIS-B)?
A
- Offered through ADS-B Flight deck display of aviation weather and aeronautical information
- Is not real time Wx info
- Delayed 5-15 minutes
23
Q
What is a METAR and what are two types?
A
- Meteorological Aerodrome Report
- Hourly report of surface observations at airport
- Types:
- Routine
- Special
24
Q
Aviation Area Forecast (FA)
A
- Specified wx phenomena covering a flight info region
- Used to
- Determine en route forecast
- Interpolate conditions at airport without TAF
- Issued 3 times daily
25
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
26
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
27
What is a Wx Depiction Chart?
* Graphical depiction of METAR info
* Issued 8 times daily
* Valid for 8 hours
* Flight planning tool to see overall current surface conditions
* Shows VFR/MVFR/IFR/LIFR
28
What are Short Range Surface Prognostic Charts?
* Forecast of surface pressure systems, fronts, and precipitation for 2 ½ days
* Issued 4 times daily
* Forecast periods of 12, 18, 24, 48, and 60 hours
* Shows a progressive view of wx over next 48 -60 hrs
29
What is included in a METAR?
1. ICAO
2. Date/Time of issuance
3. Wind Velocity & Direction
4. Visibility
5. Sky Condition/Clouds
6. RVR
7. Wx Phenomena (-RA, +SN, etc)
8. Temp/Dew Point
9. Altimeter Setting
10. Remarks
11. Automation Type (AO1/AO2)
30
How many times daily is a TAF issued?
4 times daily
31
Types of Airmets
* Sierra - IFR conditions, mountain obscurations
* Tango - Turbulence
* Zulu - Freezing Conditions
32
Types of Wx observing programs?
* Manual
* AWOS
* Automated Wx Observing System
* Transmits minute-by-minute weather observations directly to the pilot
* ASOS/AWSS
* Automated Surface Observation System/Automated Wx Sensor System.
* Minute-by minute observations generating METARS and other aviation weather information, transmitted directly to the pilot.
33
Types of Icing?
* Induction Icing
* Structural Icing
* Instrument Icing
34
IFR
500'-1000' ceiling and/or 1 mile to 3 miles visibility
35
LIFR
Less than 500' ceiling and/or less than 1 mile visibility
36
VFR
More than 3000' ceiling and more than 5 miles visibility
37
MVFR
1000'-3000' ceiling and/or 3 miles to 5 miles visibility
38
Preflight Planning Wx Charts
1. Surface analysis chart
2. Wx depiction chart
3. Short range surface prognostic chart
4. Significant Wx chart
5. Convective outlook chart
6. Constant pressure analysis
39
Info contained in Area Forecast charts
1. Synopsis
2. Clouds and Wx
* Cloud amount, bases and types,
3. Precipitation
4. Visibility
5. Winds 20kt+
6. 12-18 hour categorical outlook (VFR, IFR, etc)
40
Standard temperature and pressure
* 29.92" Hg
* 15 degrees C
41
What is a "ridge"?
* Elongated area of high pressure
* Area of descending air
* Descending air favors dissipation of clouds and good weather
42
What is a "trough"?
* Elongated area of low pressure
* Air can not go further down or outward, so it rises
* Rising air produces cloudiness, precipitation, and bad weather
43
What factor primarily determines the type and vertical extent of clouds?
Stability of the atmosphere
44
How do you determine the stability of the atmosphere?
* Unstable air
* Temp decreases uniformly and rapidly as you climb
* Likely when air near surface is moist and warm
* Surface heating, cooling aloft, converging or upslope winds, or invading air may lead to instability
* Stable air
* Temp remains unchanged or decreases slightly with altitude
45
List effects of stable vs. unstable air on clouds, turbulence, precipitation, and visibility
46
How to estimate cloud bases based on temp/dew point spread?
Formula shown in Celcius
47
Definition of "freezing level"?
* Lowest altitude in atmosphere over given location at which temp is below 0 degrees celcius
* Possible to have multiple freezing layers with temperature inversion
48
Where to check icing forecast/freeze level?
* Area forecast
* PIREPS
* AIRMETS
* SIGMETS
* Low level Significant Wx Charts
49
What conditions are necessary for structural icing?
* Visible moisture
* Below freezing temperatures
50
Types of structural icing?
* Rime Ice
* Forms when drops are small
* Freezes rapidly before liquid spreads
* Clear Ice
* Liquid flows before it freezes
* Mixed Ice
51
What is recommended if you encounter icing conditions?
* Change course and/or altitude
* Usually climb to a higher altitude, if possible
52
Is frost hazardous in flight? Why?
* Yes
* Roughness spoils smooth flow of air and slows airflow, causing loss of lift
53
Two basic ways fog forms
1. Cooling air to dew point
2. Adding moisture to air near ground
54
Where can you obtain a Wx briefing?
* Telephone Info Briefing Service
* 1-800-Wx Brief
* Private industry sources
* DUATS
* In AK, Transcribed Wx Broadcast (TWEB) and telephone TWEB
55
Where do you find listing of AFSS/FSS and Wx informaiton numbers?
* Airport/Facility Directory
* US Government section of local telephone directory
56
Types of briefings available?
* Standard
* Abbreviated
* Outlook
* Inflight
57
What is EFAS?
* En Route Flight Advisory Services
* Provides en route AC with Wx advisories pertinent to type of flight, route, and altitude
* Central collection point for PIREPs
* Between 5000' AGL to 17,500 MSL
* 122.0 MHz
58
What are PIREPs?
* Conditions observed by pilots en route
* UA = Normal
* UUA = Urgent
59
What are Inflight Aviation Wx Advisories?
* Forecasts to advise enroute AC of developing hazardous Wx
* AIRMET
* SIGMET
* Convective SIGMET
* Ceilings referenced in AGL
* All other heights referenced in MSL
60
What is an AIRMET?
* Hazardous Wx of lesser intensity than SIGMET
* Issued every 6 hours
* Details about:
* IFR
* Extensive mountain obscuration
* Turbulence
* Strong surface winds
* Icing
* Freezing levels
61
What valuable information can you derive from Winds and Temperatures Aloft forecast?
* Favorable altitude
* Areas of possible icing
* Temperature inversions
* Turbulence
62
What are radar summary charts?
* Displays areas of precipitation, including:
* Type
* Intensity
* Configuration
* Coverage
* Echo top
* Cell movement
* Severe Wx watches plotted if in effect
* Aids in preflight by showing general areas and movement of precipitation and TS
* Does not show fog or clouds
63
What are Wx Radar Reports?
* Textual info about precipitation gathered by radar
* Info about
* Location
* Time
* Configuration
* Converage
* Precipitation type
* Intensity
* Max. tops
* Cell movement
* Remarks
64
Describe US Low Level Significant Wx Chart
* Surface to FL240
* 12 and 24 hours
* Shows forecast positions, pressure systems, fronts, and precipitation
65
Describe Mid Level SIGWX chart
* 10,000' MSL to FL240
* Forecast and overview of significant en route weather phenomena
* 24 hour forecast issued 4 times daily
66
What is a Convective Outlook Chart?
* Area forecasts with potential for severe and non-severe convection and specific severe Wx threats during following 3 days
* Defines areas of slight risk, moderate risk, or high risk for 24 hour period
* Day 1 and Day 2 also show general convective outlook
