Oral Exam: Weather Information Flashcards
(82 cards)
1
Q
Explain the air flow characteristics of high and low pressure systems in the Northern Hemisphere…
A
Low Pressure: Air flows inward, upward, and counter-clockwise.
High Pressure: Air flows outward, downward, and clockwise.
2
Q
What kind of weather is expected if flying towards a low pressure system?
A
A low pressure system is characterized by rising air, which is conducive to cloudiness, precipitation, and bad weather…
3
Q
What kind of weather is expected if flying towards a high pressure system?
A
A high pressure system is characterized by descending air, which tends to favor the dissipation of cloudiness and overall good weather.
4
Q
Describe a Cold Front…
A
-Cold Front: occurs when a mass of cold, dense, and stable air advances and replaces a body of warmer air.
5
Q
Describe an Occluded Front…
A
-Occluded Front: A frontal occlusion occurs when a fast-moving cold front catches up with a slow-moving warm front (warm and cold front occlusions exist)
6
Q
Describe a Warm Front…
A
-Warm Front: The boundary area formed when a warm air mass contacts and flows over a colder air mass.
7
Q
Describe a Stationary Front…
A
-Stationary Front: When the forces of two air masses are relatively equal, the boundary or front that separates them remains stationary and influences the local weather for days. The weather is typically a mixture of both warm and cold fronts.
8
Q
What kind of weather would a pilot experience near a cold front?
A
As the cold front passes, expected weather can include towering cumulus or cumulonimbus clouds, heavy rain & lightning, thunder and or hail, possible tornados…
-Poor visibility, variable and gusting winds, rapidly dropping barometric pressure and temperature/dew point.
9
Q
What kid of weather would a pilot experience near a warm front?
A
As the warm front passes, expected weather can include stratiform clouds, drizzle, low ceilings and poor visibility, variable winds and a rise in temperature.
10
Q
What is a trough?
A
A trough(line) is an elongated are of relatively low atmospheric pressure.
- It is essentially an area of rising air.
- When air converges at the surface in a low pressure system, it cannot go outward against pressure gradient or down to the ground so it must ascend.
- Rising air in a low pressure system is conducive to cloudiness and precipitation(bad weather)
11
Q
What is a ridge?
A
A ridge(line) is an elongated are of relatively high atmospheric pressure. Air moving out of a high/ridge depletes the quantity of air.
- Therefore these are areas of descending air.
- Descending air favors the dissipation of cloudiness (good weather)
12
Q
What are standard pressure and temperature at sea level?
A
15* C and 29.92”Hg
13
Q
What are isobars?
A
An isobar is a line on a weather chart which connects areas of equal/constant barometric pressure.
14
Q
When isobars are relatively close together on a surface weather chart or constant pressure chart, what is indicated?
A
When isobars are spaced very close together, a steep pressure gradient exists which indicates higher wind speeds.
-a shallow pressure gradient exists when isobars are not close together and indicates the wind speeds will be less.
15
Q
What causes the winds aloft to flow parallel to the isobars??
A
The Coriolis force causes winds aloft to flow parallel to the isobars.
16
Q
Why do surface winds generally flow across the isobars at an angle?
A
Surface friction causes winds to generally flow across isobars at an angle.
17
Q
At what rate does atmospheric pressure decrease with an increase in altitude?
A
Pressure decreases at a rate of 1”Hg for every 1,000 feet increase in altitude.
18
Q
What does dew point mean?
A
Dew point is the temperature at which a sample of air must be cooled to in order to attain a state of saturation….
19
Q
When temperature and dew point are close together (within 5*) what type of weather is likely?
A
Visible moisture in the form of clouds, dew, or fog are likely when dew point and temperature converge.
-These conditions are ideal for carb icing too!
20
Q
What factor primarily determines the type and vertical extent of clouds?
A
The stability of the atmosphere determines the type and vertical extent of clouds!
21
Q
What is the difference between a stable atmosphere and an unstable atmosphere?
A
The stability of an atmosphere depends on its ability to resist vertical motion….
-In a stable atmosphere, vertical movement is difficult. Small vertical disturbances dampen out and disappear.
-In an unstable atmosphere, small vertical disturbances become larger resulting in turbulent airflow and convective activity. Instability can lead to significant turbulence, extensive vertical clouds, and severe weather.
22
Q
What are some STABLE atmospheric conditions?
A
- Stratiform Clouds
- Smooth air
- Steady precipitation
- Fair to poor visibility
23
Q
What are some UNSTABLE atmospheric conditions?
A
- Cumuliform Clouds
- Rough air/turbulence
- Showery/off&on precipitation
- Good visibility
24
Q
How thick should you expect the clouds to be when experiencing significant precipitation at the surface?
A
Significant precipitation usually requires clouds to be at least 4,000 feet thick… The heavier the precipitation, the thicker the clouds are likely to be.
25
During preflight planning, what weather information should you be aware of in regards to icing?
- Location of fronts: A front's location, type, speed, and direction of movement.
- Cloud layers:The location of cloud bases and tops in order to determine if you will climb above icing layers or descend beneath those layers into warmer air. (use PIREPs and area forecasts)
- Freezing levels: Important when determining how to avoid icing and how to exit icing conditions if encountered
- Air temperature and pressure: Icing tends to be found in low-pressure areas and at temperatures at or around freezing.
26
Define freezing level and how do you determine where it is?
The freezing level is the lowest altitude in the atmosphere over a specific location at which the air temperature reaches 0*C.
- Multiple freezing layers can occur if a temperature inversion exists above the defined freezing level.
- Use current icing products (CIP), forecast icing products (FIP), & freezing level graphics chart to determine the approximate freezing level.
- Other sources of icing information are area forecasts, PIREPs, AIRMETs, SIGMETs, surface analysis charts, low-level significant weather charts, and winds&temperatures aloft...
27
What conditions are necessary for structural icing to occur?
Structural icing occurs when flying through visible moisture and air temperatures at or below freezing.
28
What types of icing can a pilot encounter while flying?
Structural, induction system, and instrument icing.
29
What is clear ice?
-Clear Ice: forms after rain impacts the plane and liquid flows out over the surface. It freezes gradually as a smooth sheet of solid ice.
30
What is Rime Ice?
-Rime Ice: forms when droplets are small like those found in stratified clouds or light drizzle. The portion of drops remaining after impact freeze rapidly before the liquid has time to spread out over the aircraft surface.
31
What is Mixed Ice?
-Mixed Ice: Forms when drops vary in size or when liquid is mixed with snow and ice particles. The ice particles become imbedded in clear ice, causing a very rough accumulation.
32
What action is recommended if you encounter icing conditions?
You should leave the area of visible moisture immediately. Descend to an altitude below the cloud bases or climb to an altitude above the cloud tops, or turn to a different course.
33
Is frost considered to be hazardous to flight?
Yes because its accumulation on the aircraft spoils the smooth flow of air, causing early airflow separation.
- This results in a loss of lift, which can prevent an aircraft from becoming airborne at normal takeoff speeds.
- It can also increase stall speeds making turns and gusting winds dangerous.
34
What factors must be present for a thunderstorm to form?
- Sufficient water vapor
- An unstable lapse rate
- An initial upward boost of air to start the storm process.
35
What are the 3 stages of a thunderstorm?
1) Cumulus Stage: Updrafts cause raindrops to increase in size.
2) Mature Stage: Rain at earths surface, falling through or adjacent to updrafts. Lightning and possible roll clouds.
3) Dissipating Stage: Downdrafts and rain begin to dissipate.
36
What is a temperature inversion?
A temperature inversion occurs when temperature increases as altitude increases.
- normally, temperature decreases as altitude increases...
- An inversion aloft permits warm rain to fall through cold air below. The temperature of this cold air can be critical to icing.
- An inversion at the surface is causes by terrestrial radiation and leads to poor visibility by trapping fog, smoke, etc., into low levels of the atmosphere.
- The air is stable with little or no turbulence.
37
What are 2 basic ways fog can form?
1) Cooling air to the dew point.
| 2) Adding moisture to the air near the ground.
38
What are the 5 main types of fog?
```
Radiation fog
Advection fog
Upslope fog
Steam fog
Frontal fog / precipitation induce fog
```
39
What causes radiation fog to form?
The ground cools the adjacent air to the dew point on calm, clear nights.
40
What is advection fog, and where is it most likely to form?
Advection fog results from the transport of warm humid air over a cold surface. A pilot can expect advection fog to form primarily along coastal areas during the winter.
- It may occur with winds and or cloudy skies.
- May also occur any time of day or night and over a wide geographic area.
41
What is upslope fog?
Upslope fog forms as a result of moist, stable air being cooled adiabatically as it moves up sloping terrain. Once the upslope wind ceases, the fog dissipates.
-Upslope fog is often quite dense and extends to high altitudes.
42
What is wind shear and where is it most likely to occur?
Wind Shear: A sudden change in wind speed and or direction over a short distance in the atmosphere. It may be a horizontal shift, a vertical shift, or a combination. It may occur anywhere and is most dangerous to pilots while taking off or landing. (Low-Level)
3 areas of special concern are....
1) Wind shear with a low-level temperature inversion
2)Wind shear in a frontal zone or thunderstorm
3)Clear air turbulence(CAT) at high levels associated with a jet stream or strong circulation.
43
What types of weather information will you examine to determine if wind shear conditions might affect your flight?
- Terminal Forecasts: Be aware of any LLWS reports or the possibility of severe thunderstorms, heavy rain, hail, and wind gusts.
- METARs: be aware of any indication of thunderstorms, ran, or blowing dust. Also look out for warming trends, gusty winds, or cumulonimbus clouds.
- SIGMETs (and Convective SIGMETs): Severe convective weather is a prime source for wind shear and microbursts.
- LLWAS(Low-level wind shear alert system): installed at at 110 airports in U.S. and can detect wind shifts near by.
- PIREPs: pilot reports of sudden airspeed changes on departure/approach and landing corridors are a real time indication to the presence of wind shear.
44
What is the primary means of obtaining a weather briefing?
(FSS) The flight service station is the primary source for obtaining preflight and inflight weather briefings.
- 1-800-WX-BRIEF
- (DUATS) Direct User Access Terminal System
- (DUATSII) Lockheed Martin Flight Services
45
What are some other sources of viable weather information?
- The telephone information briefing service(TIBS)
- Private industry sources
- Aviationweather.gov
- DUATS over the internet
46
Does weather data provided by commercial or third party vendors satisfy the preflight action required by 14 CFR 91.103?
Weather services not provided by the FAA or NWS or affiliates like DUATS may not meet quality control standards.
-If in doubt, contact FSS
47
What types of weather briefings are available from an FSS briefer?
- Standard Briefing: A full briefing used while planning a flight. Should be the initial one requested.
- Abbreviated Briefing: requested when you need information to supplement weather data already collected or update a previous briefing.
- Outlook Briefing: Requested whenever your proposed time of departure is six or more hours from the time of the briefing. For planning purposes only...
- Inflight Briefing: Requested while flying to update a previous preflight briefing.
48
What pertinent information should a weather briefing include?
```
Adverse Conditions
VFR Flight not recommended
Synopsis
Current conditions
Enroute forecast
Destination forecast
Winds Aloft
Notices to Airmen (NOTAMs)
ATC Delays
Extras: MOAs, TFRs, special use airspace, alert areas, warning areas, density alt. data, etc,.
```
49
What is HIWAS?
Hazardous In-Flight Weather Advisory Service: A continuous broadcast of in-flight weather advisories including Warnings, SIGMETS(Reg & Convective), AIRMETS, urgent PIREPs, etc,.
50
What is a flight information service (FIS)?
Flight Information Service-Broadcast(FIS-B): a ground broadcast service provided by the Automatic Dependent Surveillance-Broadcast(ADS-B) services network.
-Provides pilots of properly-equipped aircraft with a display of aviation weather and aeronautical information.
51
Can onboard datalink weather (FIS-B) be useful in navigation an aircraft safely around an area of thunderstorms?
This weather information is not real-time.... It is typically updated every 5 minutes and can be up to 15 minutes old before displayed in the cockpit....
-It is not appropriate for tactical avoidance of sever weather.
52
While enroute, how can a pilot obtain updated weather information?
- FSS on 122.2
- ATIS broadcasts along your route
- HIWAS
- Datalink weather (FIS-B) from ADS-B
- ATC
53
What is a METAR? Explain both types...
METAR is an hourly surface observation of conditions observed at an airport.
- Routine: transmitted every hour...
- Special(SPECI): Special report that can be given at any time to update the METAR for rapidly changing weather conditions, aircraft mishaps, or other critical information....
54
Describe several types of weather observing programs.
Manual observations: reports from airport locations staffed by FAA personnel who manually enter their observations into the communication system.
AWOS: (Automated Weather Observing System) Comprised of various sensors, a processor, computerized voice, and a transmitter to broadcast local, minute by minute weather directly to pilots.
ASOS: (Automated Surface Observing System) Provides minute by minute observations that generate METARs and other aviation weather information. Transmitted over discrete VHF radio frequency or the voice portion of a local NAVAID. Can be received up to 25NM away from station and 10,000ft AGL....
55
What are PIREPs? Where are they usually found?
A PIREP is a pilot report of the weather conditions observed during flight. Very useful tool to confirm cloud bases and tops, wind shear, icing conditions, and turbulence...
- There are routine and urgent PIREPs. Urgent PIREPs should be reported immediately to the ground facility with which communications have been established(FSS/ATC)
- You can find PIREPs from a FSS and from aviationweather.gov
56
What are TAFs?
TAFs = Terminal Aerodome Forecasts
-a concise statement of the expected meteorological conditions significant to aviation for a specified time period within five statute miles of the center of the airport's terminal.
57
Define aviation area forecast
(FA)=Aviation Area Forecast:
-A forecast of specified weather activity covering a flight information region or other area designated by the meteorological authority.
-Should be used with other sources to determine en route weather conditions at airports with no terminal aerodrome forecasts(TAFs).
-Issued 3 times a day for each of the 6 areas in the continental US.
....REPLACED by GFAs
58
What is a GFA (Graphical Forecast for Aviation)???
GFA is intended to provide the necessary aviation weather information as a complete picture of the weather that may impact a flight in the continental US.
-includes observational data, forecasts and warnings that can be viewed from 14 hours in the past to 15 hours in the future.(Thunderstorms, clouds, precipitation, icing, wind, and turbulence.)
59
What are the four types of Inflight Aviation Weather Advisories?
-SIGMET(WS)
-Convective SIGMET (WST)
-AIRMET (WA)
Center Weather Advisory (CWA)
60
What is a convective SIGMET???
Convective SIGMET implies sever or greater turbulence, sever icing, and low-level wind shear.... May be issued for any convective situation found to be hazardous to all aircraft.
- Valid for up to 2 hours
* Severe thunderstorms due to...
- surface winds greater or equal to 50knots
- Hail at surface greater or equal to 3/4inchs
- Tornados
* Embedded thunderstorms
* A line of thunderstorms
* Thunderstorms producing heavy precipitation affecting 40% or more of an area at least 3,000 square miles.
61
What is a SIGMET?
A SIGMET- advisories of weather that is potentially hazardous to all aircraft. They are unscheduled products that are valid for 4 hours unless associated with tropical cyclones and volcanic ash clouds; then they are valid for 6 hours.
- Issued when....
* Severe icing not associated with thunderstorms
* Sever or extreme turbulence or clear air turbulence not associated with thunderstorm
* Widespread dust storms/sandstorms lowering surface visibilities to below 3 miles
* volcanic ash
62
What is an AIRMET?
AIRMET - Advisories of significant weather that describe conditions less severe than those reserved for SIGMETs.
- Intended for the use by ALL pilots during preflight planning and the enroute phases of flight to enhance safety!
- Available as text bulletins or graphics...
- AIRMETs contain details about IFR, mountain obscuration, turbulence, strong surface winds, icing, and freezing levels!
63
What are the different types of AIRMETs?
SIERRA = IFR conditions and/or mountain obscuration...
TANGO = moderate turbulence, sustained surface winds of 30 knots or greater, and/or nonconvective low-level wind shear...
ZULU = moderate icing and provides freezing level heights....
64
describe the winds and temperature aloft forecasts.....
Computer prepared forecasts of wind direction, wind speed, and temperatures at specified times, locations, and altitudes.
- Essential information for flight planning.
- Issued 4 times daily
65
What is some valuable information determined from Winds and Temps aloft Forecasts??
- Most favorable altitude
- Areas of possible icing
- Temperature Inversions
- Turbulence
66
What are (CWA) Center Weather Advisories?
CWAs are an aviation warning for use by aircrews to anticipate and avoid adverse weather conditions in the en route and terminal environments.
- not for flight planning
- reflects current conditions or forecasted conditions up to 2 hours.
67
What are some NWS weather charts you will use during preflight planning?
- Surface analysis chart
- Weather depiction chart
- short-range surface prognostic chart
- significant weather prognostic chart
- Convective outlook chart
- Constant pressure analysis chart
68
What is a surface analysis chart?
Surface analysis charts are comprised of surface weather observations.
- They include sea level pressure, position of highs/lows/ridges/troughs, location and character of fronts, boundaries like dry lines/outflow boundaries/sea-breeze fronts/convergence lines.
- Issued 8 times daily
69
What is a weather depiction chart?
Weather depiction charts contain a plot of weather conditions at selected METAR stations and an analysis of weather flying categories (VFR,MVFR,IFR)
- Used primarily as a briefing tool to alert aviation community of the location of critical operational minimums.
- issued 8 times daily
70
Define the terms LIFR, IFR, MVFR, VFR....
LIFR = low instrument flight rules: ceiling less than 500ft and/or visibility less than 1 mile
IFR = Instrument flight rules: Ceiling 500ft to less than 1000ft and/or visibility 1 to less than 3 miles
MVFR = Marginal visual flight rules: ceiling 1000 to 3000 ft and/or visibility 3 to 5 miles inclusive.
VFR = Visual Flight Rules: Ceiling greater than 3000 ft and visibility greater than 5 miles; includes sky clear!
71
What are short-range prognostic charts?
Short-range surface prognostic charts provide a forecast of surface pressure systems, fronts and precipitation for a 2 and a half day period.
-Predicted conditions divided into 5 forecast periods... 12/18/24/48/60 hours
72
What is a low-level significant weather prognostic chart?
A low-level significant weather prog chart(SIGWX) forecasts aviation weather hazards for altitudes below 24,000ft(FL240) primarily for preflight planning.
- Issued 4 times a day for a 12 hour and a 24 hour prognostic
- Depicts weather flying categories, turbulence, and freezing levels.
73
What is a mid-level significant weather chart?
A mid-level significant weather chart provides a forecast and an overview of significant en route weather phenomena for flight levels of 10,000ft MSL up to FL450.
-Issued 4 times a day for a 24hr period
74
What is a convective outlook chart?
The convective outlook chart depicts areas forecast to have the potential for severe and non-severe convection and other specific severe weather threats for three days.
- Defines areas of slight/moderate/high risk of sever thunderstorms.
- also depicts areas of general thunderstorms
75
What are constant pressure analysis charts?
Any surface of equal pressure in the atmosphere is a constant pressure surface...
- These charts are an upper air weather map in which all information is at the specified pressure of the chart...
- Air temp, wind, and temp/dew point spread along a proposed route can be found using these charts...
- They also depict highs, lows,troughs, and ridges aloft.
76
What is a microburst and where do they most likely occur?
A microburst is an intense down-draft/column of air capable of destruction similar to that of a tornado, but short lived.
-most likely to occur in an anvil like thunderstorm supercell!
77
what is a sea breeze and why does it occur?
A sea breeze occurs on hot summer days because the land heats up faster than the water.
- The warm air over land rises and the cooler air over the water flows in to replace it creating a "sea breeze"
- The process is reversed in the evening creating a "land breeze"
78
What is a mountain wave?
Mountain waves occur when strong winds blow over mountains or high ground.
- This causes the wind to oscillate on the downwind side of mountains or high ground.
- This phenomenon creates updrafts and downdrafts along with sever turbulence at the bottom of these mountain waves where the air spins. (Dangerous for pilots!)
79
Define the term ceiling...
A ceiling refers to the height of the base of the lowest clouds covering more than half of the sky.
80
What charts and reports would you use to identify the potential and location of thunderstorms along your route?
I would check out convective forecast charts and look for any SIGMETs and/or Convective SIGMETs.
- Aviation Surface Forecasts are also another good place to look for thunderstorm activity.
- Radar is another good tool
- The GFA thunderstorm chart is a great tool
- Low level significant weather prognostic charts
81
If your destination doesn't have a Terminal Forecast (TAF), what source should be referenced for weather?
The aviation area forecast(FA) has been discontinued so the best source of weather information for a destination without a TAF is the (GFA) Graphical Forecasts for Aviation.
82
What can you do before departure and en route to reduce the overall risk of the ever-changing weather environment?
Foreflight with ADS-B in provides inflight weather information along with HIWAS and Flight Watch services. PIREPs and ATC(if workload permits) can also be helpful while en route.
-While on the ground double check weather forecasts used to plan flight and get an abbreviated briefing from the FSS. Check weather radar forecasts too.
