Weather Flashcards
The average height of the troposphere in the middle latitudes is
37,000 feet
When is the wind group at one of the forecast altitudes omitted at a specific location or station in the winds and temperatures aloft forecast (FB)? When the wind
at the altitude is within 1,500 feet of the station elevation
Where does wind shear occur?
With either a wind shift or a wind speed gradient at any level in the atmosphere.
A station is forecasting wind and temperature aloft at FL 390 to be 300 degree at 200 knots; temperature -54 degree C. How would this data be encoded in the FB?
809954
Pilots on IFR flights seeking ATC in flight weather avoidance assistance should keep in mind that
ATC radar limitations and frequency congestion may limit the controllers capability to provide this service
In the northern hemisphere, surface wind spirals clockwise and outward from high pressure and counterclockwise and inward into low pressure. Where would wind not be consistent with this concept?
over mountainous areas
What is the expected duration of an individual microburst?
seldom longer than 15 minutes from the time the burst strikes the ground until dissipation
The amount of water vapor which air can hold largely depends on
air temperature
Which clouds have the greatest turbulence?
cumulonimbus
What is an important characteristic of wind shear?
It may be associated with either a wind shift or a wind speed gradient at any level in the atmosphere.
What is the maximum forecast period for AIRMETs?
six hours
Which surface of the airplane accumulates more ice first?
the tailplane
In which situation is advection fog most likely to form?
an air mass moving inland from the coast in winter
In severe icing conditions, accumulation of ice on the wing aft of the deicing boot but in front of the aileron may cause
roll upset
Thrust is managed to maintain IAS, and glideslope is being flown. What characteristics should be observed when a headwind shears to be a constant tailwind?
PITCH ATTITUDE: Decreases; REQUIRED THRUST: Increased, then reduced; VERTICAL SPEED: Increases; IAS: Decreases, then increases to approach speed
Which weather product is a concise statement of the expected weather for an airport runway complex?
Terminal Aerodrome Forecast (TAF)
Why is frost considered hazardous to flight operation?
Frost causes early airflow separation resulting in a loss of lift
The use of airborne weather-avoidance radar
provides no assurance of avoiding instrument weather conditions
What is an operational consideration if you fly into rain which freezes on impact?
Temperatures are above freezing at some higher altitude
While flying a 3 degree glideslope, a constant tailwind shears to a calm wind. Which conditions should the pilot expect?
Airspeed and pitch attitude increase and there is a tendency to go above glideslope
Graphical Forecasts for Aviation (GFA) are weather charts best used to
learn the forecast weather along your proposed route of flight as well as your destination if it has no terminal forecast
When climbing or descending through a temperature inversion or an area of possible wind shear, the pilot should be aware of
a rapid change of airspeed
What is the correct procedure to recover from roll upset?
lower the angle of attack and adjust the power for a controlled descent
What type clouds can be expected when an unstable air mass is forced to ascend a mountain slope?
Clouds with extensive vertical development
A ceiling is defined as the height of the
lowest layer of clouds or obscuring phenomena aloft that is reported as broken or overcast
In what localities is advection fog most likely to occur?
coastal areas
What type of clouds will be formed if very stable moist air is forced upslope?
stratified clouds with little vertical development
What wind direction and speed is represented by the entry 9900+00 for 9000 feet, on a winds and temperatures aloft forecast (FB)?
light and variable; less than 5 knots
A high cloud is composed mostly of
ice crystals
What are the requirements for the formation of a thunderstorm?
sufficient moisture, an unstable lapse rate, and a lifting action
A generally recommended practice for autopilot usage during cruise flight in icing conditions is
periodically disengaging the autopilot and hand flying the airplane
Which is a characteristic of stable air?
Stratiform clouds
When operating an airplane equipped with deicing boots, when is the appropriate time to turn them on?
As soon as ice starts to develop on the boot or per the manufacturer’s recommendations
What is the time frame for the validity of low-level significant weather prog charts?
12 to 24 hours in the future
What situation is most conducive to the formation or radiation fog?
Warm, moist air over low, flatland areas on clear, calm nights
Which meteorological condition is issued in the form of a SIGMET (WS)?
Widespread sand or dust storms affecting at least 3000 square miles or an area deemed to have a significant effect on the safety of aircraft.
Frontal waves normally form on
slow moving cold fronts or stationary fronts
Where can supercooled large drops (SLD) form?
In freezing precipitation below a cloud deck
What is an indication that downdrafts have developed and the thunderstorm cell has entered the mature stage?
Precipitation begins to fall from the cloud base
To which meteorological condition does the term dew point refer?
the temperature to which air must be cooled to become saturated
When a climb or descent through an inversion or wind shear zone is being performed, the pilot should be alert for which of the following change in airplane performance?
A sudden change in airspeed
What relationship exists between the winds at 2000 feet above the surface and the surface winds?
The winds at 2000 feet tend to parallel the isobars while the surface winds cross the isobars at an angle toward lower pressure and are weaker.
Preventing ice from causing a hazard for aircraft certificated for flight into known icing conditions is accomplished by
1. spraying alcohol or glycol solution on the aircraft before takeoff
2. a deicing system on the aircraft, or
3. an anti-icing system on the aircraft
Which statement(s) is/are true?
only statements 2 and 3 are true
If you fly into severe turbulence, which flight condition should you attempt to maintain?
level flight attitude
What temperature condition is indicated if wet snow is encountered at your flight altitude?
the temperature is above freezing at your altitude
If squalls are reported at your destination, what wind conditions should you anticipate?
Sudden increases in wind speed or at least 16 knots, rising to 22 knots or more, lasting for at least 1 minute
When passing through an abrupt wind shear which involves a shift from a tailwind to a headwind, what power management would normally be required to maintain a constant indicated airspeed and ILS glideslope?
Lower than normal power initially, followed by a further decrease as the wind shear is encountered, then an increase
The presence of standing lenticualr altocumuls clouds is a good indication of
very strong turbulence
The general characteristics of unstable air are
good visibility, showey precipitation, and cumuliform type clouds
Which of the following combinations of weather producing variables would likely result in cumuliform type clouds, good visibility, rain showers, and possible clear type icing in clouds?
unstable, moist air, and orographic lifting
If you encounter in flight icing and ATC asks you to report your conditions, what are the official reportable icing values that you are expected to use?
Trace, light, moderate, severe
Fair weather cumulus clouds often indicate
turbulence at and below the cloud level
Standing lenticular clouds, in mountainous areas, indicate
turbulence
The most hazardous aspect of structural icing is
aerodynamic degradation including loss of lift
A characteristic of the stratosphere is
relatively small changes in temperature with an increase in altitude
An aircraft that encounters a headwind of 45 knots, within a microburst, may expect a total shear across the microburst of
90 knots
The low level significant weather prognostic chart depicts weather conditions
that are forecast to exist at a valid time shown on the chart
Where do squall lines most often develop?
Ahead of a cold front
What are some characteristics of unstable air?
Turbulence and good surface visibility
Unsaturated air flowing upslope will cool at the rate of approximately (dry adiabatic lapse rate)
3 degree C per 1000 feet
Which meteorological conditions are depicted by a prognostic chart?
Conditions forecast to exist at a specific time shown on the chart
The strength and location of the jetstream is normally
weaker and farther north in the summer
During the life cycle of a thunderstorm, which stage is characterized predominately by downdrafts?
dissipating
In which meteorological environment is aircraft structural icing most likely to have the highest rate of accumulation?
freezing rain
Which conditions result in the formation of frost?
Temperature of the collecting surface is below the dew point of surrounding air and the dew point is colder than freezing
SIGMETs are unscheduled weather products that are valid for
a period not to exceed 4 hours, but may be reissued for additional 4 hour periods
What happens to residual ice that remains after deice boots are inflated and shed ice?
Residual ice increases with a decrease in airspeed or temperature
Winds at 5000 feet AGL on a particular flight are southwesterly while most of the surface winds are southerly. This difference in direction is primarily due to
friction between the wind and the surface
Supercooled large drops (SLD) form when
temperatures are below freezing there is a large volume of liquid water precipitation
Which feature is associated with the tropopause?
abrupt change in temperature lapse rate
What is an important characteristic of wind shear?
It is an atmospheric condition that may be associated with a low-level temperature inversion, a jet stream, or a frontal zone.
Which are characteristics of an unstable cold air mass moving over a warm surface?
cumuliform clouds, turbulence, and good visibility
Hazardous wind shear is commonly encountered near the ground
during periods of strong temperature inversion and near thunderstorms
In a coastal area with winds blowing from cool water over a warmer land mass, what type of weather might be expected?
clear skies
The most frequent type of ground or surface based temperature inversion is the produced by
radiation on a clear, relatively still night
Which force, in the northern hemisphere, acts at a right angle to the wind and deflects it to the right until parallel to the isobars?
Coriolis
The surface analysis chart depicts
actual frontal positions, pressure patterns, temperature, dewpoint, wind, weather, and obstructions to vision at the valid time of the chart
Test data indicate that ice, snow, or frost having a thickness and roughness similar to medium or coarse sandpaper on the leading edge and upper surface of an airfoil can
reduce lift by as much as 30 percent and increase drag by 40 percent
The primary cause of all changes in the Earth’s weather is
variation of solar energy received by the Earth’s regions
How should an aircraft be checked for frost during preflight?
using your hands to physically check the wings and control surfaces
A calm wind entry in a Terminal Aerodrome Forecast (TAF) will be indicated when the wind is
3 knots or less
Which weather forecast describes prospects for an area coverage of both severe and general thunderstorms during the following 24 hours?
convective outlook
A pilot planning to depart at 1100Z on an IFR flight is particularly concerned about the hazard of icing. What sources reflect the most accurate information on icing conditions (current and forecast) at the time of departure?
pilot weather reports (PIREPs), AIRMETs, and SIGMETs
Which weather phenomenon is always associated with a thunderstorm?
lightning
A jetstream is defined as wind of
50 knots or greater
Which procedure is recommended if a pilot should unintentionally penetrate embedded thunderstorm activity?
Set power for recommended turbulence penetration airspeed and attempt to maintain a level flight attitude
What types of fog depend upon a wind in order to exist?
advection fog and upslope fog
Which weather condition can be expected when moist air flows from a relatively warm surface to a colder surface?
fog
A common type of ground or surface based temperature inversion is that which is produced by
ground radiation on clear, cool nights when the wind is light
When are severe weather watch bulletins (WW) issued?
Unscheduled and issued as required
The suffix nimbus, used in naming clouds, means a
rain cloud
What is indicated by the term embedded thunderstorms?
thunderstorms are obscured by massive cloud layers and cannot be seen
Which weather phenomenon signals the beginning of the mature stage of a thunderstorm?
The start of rain at the surface
What are the characteristics of stable air?
poor visibility, steady precipitation, and stratus type clouds
While flying a 3 degree glideslope, a headwind shears to a tailwind. Which conditions should the pilot expect on the glideslope?
Airspeed and pitch attitude decrease and there is a tendency to go below glideslope.
Steady precipitation, in contrast to showers, preceding a front is an indication of
stratiform clouds with little or no turbulence
Maximum downdrafts in a microburst encounter may be as strong as
6000 feet per minute
One of the visual cues of supercooled large water droplet (SLD) conditions is
ice forming on the propeller spinner and reaching back to the propeller blades
On initial climb out after takeoff and with the autopilot engaged, you encounter icing conditions. In this situation you can expect
ice to accumulate on the underside of the wings due to the higher AOA
If a pilot encounters freezing drizzle, he can assume that
there is warmer air above him
What feature is associated with a temperature inversion?
a stable layer of air
Under which condition does advection fog usually form?
Moist air moving over colder ground or water
From which primary source should you obtain information regarding the weather expected to exist at your destination at your estimated time of arrival?
Terminal Aerodrome Forecast
A temperature inversion will normally form only
in stable air
Which thunderstorms generally produce the most severe conditions, such as heavy hail and destructive winds?
squall line
Which values are used for winds aloft forecasts?
true direction and knots
A pilot reporting turbulence that momentarily causes slight, erratic changes in altitude and/or attitude should report it as
light turbulence
When approaching a cumulonimbus cell that is on your route of flight, a pilot should
circumnavigate the cell by at least 20 nautical miles
AIRMETs are issued on a scheduled basis every
six hours
Which precipitation type normally indicates freezing rain at higher altitudes?
ice pellets
A prognostic chart depicts the conditions
forecast to exist at a specific time in the future
What are the four families of clouds?
High, middle, low, and those with extensive vertical development
What does a convective outlook (AC) describe for a following 24 hour period?
general thunderstorm activity
When is the temperature at one of the forecast altitudes omitted at a specific location or station in the winds and temperatures aloft forecast (FB)?
For the 3000 foot altitude (level) or when the level is within 2500 feet of station elevation
Clouds, fog, or dew will always form when
water vapor condenses
An air mass is a body of air that
covers an extensive area and has fairly uniform properties of temperature and moisture
In the event of suspected tailplane icing during an approach, what actions should the pilot take?
Use partial or no flaps and no autopilot
Expect clear ice to form on the leading edge of airfoils when
temperatures are close to freezing, there is a large volume of liquid water precipitation and the aircraft is at high airspeeds
While on approach, you lower flaps to approach setting and suspect tailplane ice has occurred. Which of the following statements is true regarding proper recover from a tailplane stall?
Flaps should be retracted immediately to the previous setting, appropriate nose up elevator pressure should be applied and sufficient power should be added for the airplane’s configuration
What determines the structure or type of clouds which form as a result of air being forced to ascend?
The stability of the air before lifting occurs
Which conditions are favorable for the formation of radiation fog?
clear sky, little or no wind, small temperature/dewpoint spread, and over a land surface
The body of a terminal aerodrome forecast (TAF) covers a geographical proximity within a
5 statue mile radius from the center of an airport runway complex
If severe turbulence is encountered during your IFR flight, the airplane should be slowed to the design maneuvering speed because the
amount of excess load that can be imposed on the wing will be decreased
When flying through supercooled water droplets, the first sign of structural ice accumulation would be
probes and antennas
Which family of clouds is least likely to contribute to structural icing on an aircraft?
High clouds
Which is a characteristic of low level wind shear as it relates to frontal activity?
With a warm front, the most critical period is before the front passes the airport
What enhances the growth rate of precipitation?
Upward currents
Where can wind shear associated with a thunderstorm be found? Choose the most complete answer.
On all sides of the thunderstorm cell and directly under the cell
Which weather conditions should be expected beneath a low level temperature inversion layer when the relative humidity is high?
Smooth air and poor visibility due to fog, haze, or low clouds
When the visibility is greater than 6 SM on a TAF it is expressed as
P6SM
The presence of ice pellets at the surface is evidence that
there is freezing rain at a higher altitude
Fog is usually prevalent in industrial areas because of
an abundance of condensation nuclei from combustion products
Which weather phenomenon is always associated with the passage of a frontal system?
a wind change
Stability can be determined from which measurement of the atmosphere?
ambient lapse rate
What causes surface winds to flow across the isobars at an angle rather than parallel to the isobars?
surface friction
What information is provided by a convective outlook (AC)?
It provides prospects of both general and severe thunderstorm activity during the following 24 hours
SIGMETs are issued as a warning of weather conditions potentially hazardous
to all aircraft
When flying through stratiform clouds, the best way to alleviate icing is by
changing altitude to one with above freezing temperatures or where temperatures are cooler than -10 degree C
