Ch. 3: Wx Flashcards

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1
Q

Describe characteristics of flow of air around high and low pressure systems?

A
  • High: Inward, Upward, Counterclockwise
  • Low: Outward, downward, clockwise
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2
Q

What kind of weather would you expect flying through a low pressure system?

A
  • Rising air
    • Cloudiness
    • Precipitation
    • Bad weather
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3
Q

What kind of weather would you expect flying through a high pressure system?

A
  • Descending air
    • Dissipation of clouds
    • Good weather
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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
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5
Q

Occluded Front

A

Fast moving cold front catches up to slow moving warm front

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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
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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
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8
Q

What causes winds aloft to flow parallel to the isobars?

A

Coriolis Force

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9
Q

Why do surface winds generally flow across the isobars at an angle?

A

Surface Friction

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10
Q

At what rate does atmospheric pressure decrease with an increase in altitude?

A

1” Hg per 1,000’

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11
Q

What does dew point mean?

A

Temp at which air must be cooled to become saturated

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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
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13
Q

Stages of a TS

A
  • Cumulus Stage
  • Mature Stage
  • Dissipating Stage
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14
Q

Name several types of fog

A
  1. Radiation fog
  2. Advection fog
  3. Upslope fog
  4. Frontal fog
  5. Steam fog
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15
Q

What causes radiation fog?

A

Ground cools the adjacent air to the dew point on calm, clear nights

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16
Q

What causes advection fog?

A
  • Warm humid air moves in over a cold surface
  • Primarily along coastal areas
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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
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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
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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
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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.
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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
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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
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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
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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
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25
Q

What are Center Wx Advisories?

A
  • 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
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26
Q

What is a Surface Analysis Chart?

A
  • 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
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27
Q

What is a Wx Depiction Chart?

A
  • 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
Q

What are Short Range Surface Prognostic Charts?

A
  • 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
Q

What is included in a METAR?

A
  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
Q

How many times daily is a TAF issued?

A

4 times daily

31
Q

Types of Airmets

A
  • Sierra - IFR conditions, mountain obscurations
  • Tango - Turbulence
  • Zulu - Freezing Conditions
32
Q

Types of Wx observing programs?

A
  • 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
Q

Types of Icing?

A
  • Induction Icing
  • Structural Icing
  • Instrument Icing
34
Q

IFR

A

500’-1000’ ceiling and/or 1 mile to 3 miles visibility

35
Q

LIFR

A

Less than 500’ ceiling and/or less than 1 mile visibility

36
Q

VFR

A

More than 3000’ ceiling and more than 5 miles visibility

37
Q

MVFR

A

1000’-3000’ ceiling and/or 3 miles to 5 miles visibility

38
Q

Preflight Planning Wx Charts

A
  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
Q

Info contained in Area Forecast charts

A
  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
Q

Standard temperature and pressure

A
  • 29.92” Hg
  • 15 degrees C
41
Q

What is a “ridge”?

A
  • Elongated area of high pressure
  • Area of descending air
  • Descending air favors dissipation of clouds and good weather
42
Q

What is a “trough”?

A
  • 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
Q

What factor primarily determines the type and vertical extent of clouds?

A

Stability of the atmosphere

44
Q

How do you determine the stability of the atmosphere?

A
  • 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
Q

List effects of stable vs. unstable air on clouds, turbulence, precipitation, and visibility

A
46
Q

How to estimate cloud bases based on temp/dew point spread?

A

Formula shown in Celcius

47
Q

Definition of “freezing level”?

A
  • 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
Q

Where to check icing forecast/freeze level?

A
  • Area forecast
  • PIREPS
  • AIRMETS
  • SIGMETS
  • Low level Significant Wx Charts
49
Q

What conditions are necessary for structural icing?

A
  • Visible moisture
  • Below freezing temperatures
50
Q

Types of structural icing?

A
  • Rime Ice
    • Forms when drops are small
    • Freezes rapidly before liquid spreads
  • Clear Ice
    • Liquid flows before it freezes
  • Mixed Ice
51
Q

What is recommended if you encounter icing conditions?

A
  • Change course and/or altitude
    • Usually climb to a higher altitude, if possible
52
Q

Is frost hazardous in flight? Why?

A
  • Yes
  • Roughness spoils smooth flow of air and slows airflow, causing loss of lift
53
Q

Two basic ways fog forms

A
  1. Cooling air to dew point
  2. Adding moisture to air near ground
54
Q

Where can you obtain a Wx briefing?

A
  • Telephone Info Briefing Service
    • 1-800-Wx Brief
  • Private industry sources
  • DUATS
  • In AK, Transcribed Wx Broadcast (TWEB) and telephone TWEB
55
Q

Where do you find listing of AFSS/FSS and Wx informaiton numbers?

A
  • Airport/Facility Directory
  • US Government section of local telephone directory
56
Q

Types of briefings available?

A
  • Standard
  • Abbreviated
  • Outlook
  • Inflight
57
Q

What is EFAS?

A
  • 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
Q

What are PIREPs?

A
  • Conditions observed by pilots en route
  • UA = Normal
  • UUA = Urgent
59
Q

What are Inflight Aviation Wx Advisories?

A
  • Forecasts to advise enroute AC of developing hazardous Wx
    • AIRMET
    • SIGMET
    • Convective SIGMET
  • Ceilings referenced in AGL
  • All other heights referenced in MSL
60
Q

What is an AIRMET?

A
  • 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
Q

What valuable information can you derive from Winds and Temperatures Aloft forecast?

A
  • Favorable altitude
  • Areas of possible icing
  • Temperature inversions
  • Turbulence
62
Q

What are radar summary charts?

A
  • 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
Q

What are Wx Radar Reports?

A
  • Textual info about precipitation gathered by radar
  • Info about
    • Location
    • Time
    • Configuration
    • Converage
    • Precipitation type
    • Intensity
    • Max. tops
    • Cell movement
    • Remarks
64
Q

Describe US Low Level Significant Wx Chart

A
  • Surface to FL240
  • 12 and 24 hours
  • Shows forecast positions, pressure systems, fronts, and precipitation
65
Q

Describe Mid Level SIGWX chart

A
  • 10,000’ MSL to FL240
  • Forecast and overview of significant en route weather phenomena
  • 24 hour forecast issued 4 times daily
66
Q

What is a Convective Outlook Chart?

A
  • 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