Weather Information Flashcards
What direction of air movement is associated with low pressure systems?
Inwards, upwards, and counterclockwise
What direction of air movement is associated with high pressure?
Outward, downward, clockwise
What are the types of fronts?
Cold
Occluded
Warm
Sationary
Describe a cold front.
Cold, dense, stable air moves under and replaces warm air. Typically associated with thunderstorms. Gusty winds.
Describe an occluded front.
Fast moving cold front catches up to slow, warm front. Two types cold/warm occlusion.
Describe a warm front.
Warm air moves over and replaces cold air. Stratiform clouds. Low ceilings. Poor visibility.
Describe a stationary front.
Forces of two air masses equally opposed. Several days of affected weather. Mix of both warm & cold.
What is a trough (line)?
Elongated low pressure. Air flows in and up in a trough. Precipitation likely.
What is a ridge (line)?
Elongated area of high pressure. Descending air. Good weather.
What is STP for flight in C and F.
59F - 15C
29.92”Hg - 1013.2 millibars
What are isobars?
Lines that divide areas of equal pressure on a weather chart.
What does it mean if isobars are close together?
- Steep pressure gradient.
2. Higher wind speed
Why do winds flow across isobars at an angle?
Surface friction
What rate does pressure decrease with altitude?
1” Hg per 1000 feet
What condition is air in at dew point.
Saturated
How thick are clouds (at least) if there is significant rain at the surface?
4,000+ feet thick
What meteorological data should a pilot be aware of while planning a flight?
Fronts: location, type, speed, direction
Cloud layers: bases and tops
Freezing level(s): how to avoid icing
Air temp. & press.: icing at low press. and freezing temp.
What conditions are necessary for structural icing?
- Visible moisture
2. Below freezing
What are the two categories of aircraft icing?
- Structural - airframe
2. Induction - engine
What are three types of structural icing? Describe each.
- Clear ice: After initial impact when drop flows over surface. Gradual freeze
- Rime ice: Small drops. Drop freezes fast after impact before spreading
- Mixed ice: Drops vary in size. Very rough
Is frost hazardous to flight?
Yes. It spoils smooth airflow.
What conditions must be present for thunderstorms.
- Sufficient moisture
- Unstable lapse rate
- Lifting action
What kinds of fog forms in air colder than the dew pint?
- Radiation fog
- Advection fog
- Upslope fog
What kids of fog form from excess moisture?
- Frontal fog
2. Steam fog
Name types of fog.
- Radiation fog
- Advection fog
- Upslope fog
- Frontal/precipitation-induced fog
- Steam fog
What causes radiation fog?
When the ground cools adjacent air below dew point on calm, clear nights.
Describe advection fog and its source.
Transport of humid air over a cool surface.
Coastal areas in winter. Any wind/cloud conditions. Any time. Wide area.
Describe upslope fog and its source.
Moist stable air cooled adiabatically as it moves uphill.
Powered by wind, so it needs it to exist. Dense. Extends to high altitudes.
Define wind sheer. Where does it occur.
Change in wind velocity per unit of horizontal or vertical distance.
Occurs at any level, but most common in:
- Low level temp inversion
- Fronts or thunderstorms
- Clear Air Turbulence (CAT) (from jet stream or strong circulation)
What type of weather info do pilots examine to check for wind shear?
- Terminal forecasts: any LLWS, thunderstorms, or microbursts
- METARs: thunderstorms, gusts, warming trends
- SIGMETS: prime source
- LLWAS: (LLWS alert system)
- PIREPs: sudden airspeed changes
LLWS = Low Level Wind Shear
Where can one get a weather briefing?
Flight Service Station (FSS) over the phone online.
1800wxbrief.com
What are other sources of weather?
- Private sources
- Flight Info Services (FIS-B via ADS-B in)
- Aviation weather cameras (Alaska only)
What kinds of briefings are available from an AFSS/FSS briefer?
Standard: for when no preliminary data is known
Abbreviated: supplements known data
Outlook: 6+ hours forecast for plan
//Inflight: to update preflight
What should a weather briefing include?
- Adverse conditions
- VFR flight not recommended
- Synopsis
- Current conditions
- Enroute forecast
- Destination forecast
- Winds aloft
- NOTAMs
- ATC delay
- Optional: SUA, alert areas, MOAs, MTRs, training routes, warning areas, ATCAA, density alt., immigration procedures, ADIZ rules, search & rescue, runway friction, GPS RAIM
Describe FIS-B.
Through ADS-B UAT network. Line-of-sight. Weather info.
Can you use FIS-B to avoid thunderstorms in flight?
No. It’s not real time.
Andres’s Story
Where can a pilot get inflight weather?
- FSS on 122.2 and appropriate RCO (remote communication outlet) frequencies
- ATIS/AWOS/ASOS
- ARTCC — AWWs, SIGMET family, Urgent PIREPs, CWA alerts ???
- Datalink weather
- ATC
How often is a METAR updated?
Hourly
Distinguish the two kinds of METARs
Routine: hourly
Selected Special Weather Report (SPECI): given any time for crit. info
Describe parts of a METAR.
Type of Report - METAR & SPECI ICAO Station ID - 4 letters Date & Time - 6 digit Z Modifier - AUTO or based on precip. Wind - 5 digits: 3 dir, 2 vel Visibility - surface, SM Runway Visual Range (RVR) - Weather Phenomena - qualifiers, phenomena Sky Condition - amount/height/type clouds AGL Temp/Dew Point - Celsius Altimeter - “ Hg Remarks - additional optional data
List weather observing programs.
- Manual Observations
- AWOS
- AWOS Broadcasts
- ASOS/AWOS
Describe Manual Observations.
Locations staffed by FAA. Conducted by personnel at airport.
Describe AWOS.
Automated Weather Observing System. Automatic, minute by minute weather data radioed directly to pilot. AUTO prefix.
What is a PIREP?
A weather report confirming data that can only be seen by someone in flight instead of a ground station. (Good for finding icing)
What are the two kinds of PIREPS?
UA - routine PIREP
UUA - Urgent PIREP
What is a TAF?
Terminal Aerodrome Forecast: Airport specific weather forecast organized like a METAR
Describe the parts of a TAF.
- Type of report
- ICAO ID
- Date and Time (of origin)
- Valid Time
- Forecasts
What types of TAFs are there?
- Routine (TAF)
- Amended (TAF COR)
- Corrected (TAF AMD)
What is an FA?
Aviation Area Forecast: Issued for Gulf of Mexico, Caribbean, and Alaska. 18-24 hour forecast. 3-4 times daily.
Describe GFAs.
Graphical Forecasts for Aviation: Web based graphics that show wind, icing, and turbulence in 3,000 foot increments from 6k-30k MSL and 6k increments from 30k-48k. 14 hours in the past to 15 hours in the future.
What types of forecast are available under the “Forecast” tab of the GFA on aviationweather.gov?
- TAF
- CIG/VIS - Ceiling and Visibility
- Clouds
- PCPN/WX - Precip. & weather
- Thunderstorms
- Turbulence
- Ice
What weather products are available under the “Obs/Warn” tab of the GFA?
- METAR
- Precipitation/weather
- CIG/VIS
- PIREP
- RAD/SAT - Radar/Satellite
What are the 4 inflight aviation weather advisories?
- SIGMET
- convective SIGMET
- AIRMET
- Center Weather Advisory
Ceilings are reported with which altitude?
AGL
What do convective SIGMETs report?
Thunderstorms, icing, and low level wind shear. Hazards for all categories of aircraft.
What does a SIGMET report?
- Severe icing not from thunderstorms
- Severe turbulence or CAT that is not from thunderstorms
- Dust storms/sandstorms
- Volcanic ash
Potentially hazardous to all aircraft.
What is an AIRMET
For use by ALL pilots. Lower intensity than SIGMETs. Contain details about IFR, mountain obscuration, turbulence, strong surface winds, icing, and freezing levels.
Describe the three AIRMET types.
Sierra: IFR conditions or MOUNTAIN observations
Tango: moderate Turbulence, sustained surface winds of 30kts+, or non-convective LLWS
Zulu: icing and freeZing level heights
Describe winds and temp.s aloft.
They are forecasts for wind speed and direction and temperature at altitude. 4/day.
What information can you determine from a winds aloft forecast?
- Most favorable altitude - tailwinds
- Areas of possible icing
- Temperature inversions
- Turbulence - by observing abrupt changes in wind direction
What are CWAs?
Center Weather Advisory: Aviation warning for poor weather en route or at a point. Current conditions only.
What are some NWS weather charts used in flight planning?
- Surface Analysis Chart
- Weather Depiction Chart (old) - Ceiling and Visibility Analysis (new)
- Short-range Surface Prognostic Chart
- Significant Weather Prognostic Chart
- Convective outlook Chart
- Constant Pressure Analysis Chart (old) - Upper Air Constant Pressure Level Forecasts (new)
- Freezing Level Graphics
What is a surface analysis chart? How many are made per day.
Surface weather observations. Sea level pressure, highs, lows, ridges, troughs, fronts, boundaries (like drylines). 8x/day
Describe a CVA.
Ceiling and Visibility Analysis: Real time (5 min). Displays current visibility and ceilings. Follow up with other forms of weather data.
Define LIFR
LIFR - Low IFR: ceiling <500ft or visibility <1mile
Define IFR
IFR: Ceiling 500-1000ft or visibility 1-3 miles
Define MVFR
MVFR - Marginal VFR: ceiling 1,000-3,000ft or visibility 3-5 miles
Define VFR.
VFR: Ceiling >3,000ft and visibility >5 miles
What are short-range surface prognostic charts?
prog charts forecast surface pressure systems, fronts, and precipitation for a 2.5 day period. 12, 18, 24, 48, and 60 hour predicted conditions. Issued 4x/day.
Describe a Low-Level SIGWX chart.
Low-Level Significant Weather Prog Chart: Aviation weather hazards from flight level 240 and below. Used in preflight
Describe a Mid-Level SIGWX chart.
10,000 to FL450. Snapshot of weather hazardous to aviation. 1x/day
What is a convective outlook chart?
Forecasts areas that have potential for severe weather (tornado, 50+kts, hail 3/4+”) and non severe convection weather. Slight (SGLT), Moderate (MDT), or High (HIGH) for 24 hour periods 1 and 2 days in advance.
Define Constant Pressure Analysis Charts.
Shows pressures at different altitudes. Issued twice daily, 5 charts from 00Z to 12Z.
