LETU Meteorology final Flashcards

Cumulus cloud
Terms Definitions
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.
How much colder than standard temperature is the forecast temperature at 9,000 feet, as indicated in the following excerpt from the Winds and Temperature Aloft Forecast?|FT 6000 9000| 0737-04 1043-10
The primary cause of all changes in the Earth's weather is
variation of solar energy received by the Earth's regions.
A characteristic of the stratosphere is
relatively small changes in temperature with an increase in altitude.
Steady precipitation, in contrast to showers, preceding a front is an indication of
stratiform clouds with little or no turbulence.
The presence of ice pellets at the surface is evidence that
there is freezing rain at a higher altitude.
Which conditions result in the formation of frost?
Temperature of the collecting surface is below the dewpoint of surrounding air and the dewpoint is colder than freezing.
To which meteorological condition does the term "dew point" refer?
The temperature to which air must be cooled to become saturated.
The amount of water vapor which air can hold largely depends on
air temperature.
Clouds, fog, or dew will always form when
Clouds, fog, or dew will always form when
Winds at 5,000 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.
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?
If the air temperature is +8°C at an elevation of 1,350 feet and a standard temperature lapse rate exists, what will be the approximate freezing level?
5,350 feet MSL.
What feature is associated with a temperature inversion?
A stable layer of air.
What type of clouds will be formed if very stable moist air is forced up slope?
Stratified clouds with little vertical development.
The general characteristics of unstable air are
good visibility, showery precipitation, and cumuliform-type clouds.
Which is a characteristic of stable air?
Stratiform clouds.
What type clouds can be expected when an unstable air mass is forced to ascend a mountain slope?
Clouds with extensive vertical development.
Stability can be determined from which measurement of the atmosphere?
Ambient lapse rate.
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.
Unsaturated air flowing up slope will cool at the rate of approximately (dry adiabatic lapse rate)
3°C per 1,000 feet.
Which weather phenomenon signals the beginning of the mature stage of a thunderstorm?
The start of rain at the surface.
Which are characteristics of an unstable cold air mass moving over a warm surface?
Cumuliform clouds, turbulence, and good visibility.
Which clouds have the greatest turbulence?
Standing lenticular clouds, in mountainous areas, indicate
The suffix "nimbus", used in naming clouds, means a
rain cloud.
Which family of clouds is least likely to contribute to structural icing on an aircraft?
High clouds.
What are the four families of clouds?
High, middle, low, and those with extensive vertical development.
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 phenomenon is always associated with the passage of a frontal system?
A wind change.
Where do squall lines most often develop?
Ahead of a cold front.
With either a wind shift or a wind speed gradient at any level in the atmosphere.
What is indicated by the term "embedded thunderstorms"?
Thunderstorms are obscured by massive cloud layers and cannot be seen.
During the life cycle of a thunderstorm, which stage is characterized predominately by downdrafts?
Which weather phenomenon is always associated with a thunderstorm?
Which thunderstorms generally produce the most severe conditions, such as heavy hail and destructive winds?
Squall line.
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 are the requirements for the formation of a thunderstorm?
Sufficient moisture, an unstable lapse rate, and a lifting action.
Fair weather cumulus clouds often indicate
turbulence at and below the cloud level.
Why is frost considered hazardous to flight operation?
Frost causes early airflow separation resulting in a loss of lift.
In which meteorological environment is aircraft structural icing most likely to have the highest rate of accumulation?
Freezing rain.
The average height of the troposphere in the middle latitudes is
37,000 feet.
A jet stream is defined as wind of
50 knots or greater.
Under which condition does advection fog usually form?
Moist air moving over colder ground or water.
A high cloud is composed mostly of
ice crystals.
An air mass is a body of air that
covers an extensive area and has fairly uniform properties of temperature and moisture.
What enhances the growth rate of precipitation?
Upward currents.
If you fly into severe turbulence, which flight condition should you attempt to maintain?
Level flight attitude at speeds at or below VA
Which precipitation type normally indicates freezing rain at higher altitudes?
Ice pellets.
An aircraft that encounters a headwind of 45 knots, within a microburst, may expect a total shear across the microburst of
90 knots.
The body of a Terminal Aerodrome Forecast (TAF) covers a geographical proximity within a
5 statute mile radius from the center of an airport runway complex.
What wind direction and speed is represented by the entry 9900+00 for 9,000 feet, on an Winds and Temperatures Aloft Forecast (FD)?
Light and variable; less than 5 knots.
What conclusion/s can be drawn from a 500-millibar Constant Pressure Chart for a planned flight at FL 180?
Observed temperature, wind, and temperature/dewpoint spread along the proposed route can be approximated.
What important information is provided by the Radar Summary Chart that is not shown on other weather charts?
Lines and cells of hazardous thunderstorms.
What does a Convective Outlook (AC) describe for a following 24 hour period?
General thunderstorm activity.
Which primary source should be used to obtain forecast weather information at your destination for the planned ETA?
Terminal Aerodrome Forecast (FAA No: TAF).
A "VRB" wind entry in a Terminal Aerodrome Forecast (TAF) will be indicated when the wind is
3 knots or less.
When the visibility is greater than 6 SM on a TAF it is expressed as
"WND" in the categorical outlook in the Aviation Area Forecast means that the wind during that period is forecast to be
at least 20 knots or stronger.
What is the forecast wind at 1800Z in the following TAF? |KMEM 091740Z 1818 00000KT 1/2SM RAFG OVC005=
SIGMET's are issued as a warning of weather conditions potentially hazardous
to all aircraft.
What significant sky condition is reported in this METAR observation?|METAR KBNA 1250Z 33018KT 290V360 1/2SM R31/2700FT +SN BLSNFG VV0008 00/M03 A2991 RMK RERAE42SNB42
Sky is obscured with vertical visibility of 800 feet.
Which meteorological condition is issued in the form of a SIGMET (WS)?
Widespread sand or dust storms lowering visibility to less than 3 miles.
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 (PIREP's), AIRMET's, and SIGMET's.
Which forecast provides specific information concerning expected sky cover, cloud tops, visibility, weather, and obstructions to vision in a route format?
249 TWEB 252317.
When are severe weather watch bulletins (FAA No: WW) issued?
Unscheduled and issued as required.
What is the maximum forecast period for AIRMET's?
Six hours.
When is the temperature at one of the forecast altitudes omitted at a specific location or station in the Winds and Temperatures Aloft Forecast (FD)?
For the 3,000-foot altitude (FAA No: level) or when the level is within 2,500 feet of station elevation.
Decode the excerpt from the Winds and Temperature Aloft Forecast
( FD) for OKC at 39,000 feet. |FT 3000 6000 39000|OKC 830558
Wind 330° at 105 knots, temperature -58°C.
Which values are used for winds aloft forecasts?
True direction and knots.
The station originating the following weather report has a field elevation of 1,300 feet MSL. From the bottom of the overcast cloud layer, what is its thickness? (tops of OVC are reported at 3800 feet) |SPECI KOKC 2228Z 28024G36KT 3/4SM BKN008 OVC020 28/2
500 feet.
Which response most closely interprets the following PIREP?|UA/OV OKC 063064/TM 1522/FL080/TP C172/TA -04/WV 245040/TB LGT/RM IN CLR
64 nautical miles on the 63° radial from Oklahoma City VOR at 1522 UTC, flight level 8,000 ft. Type of aircraft is a Cessna 172.
Area forecasts generally include a forecast period of 18 hours and cover a geographical
area the size of several states.
A ceiling is defined as the height of the
lowest layer of clouds or obscuring phenomena aloft that is reported as broken or overcast.
What is the wind shear forecast in the following TAF?|TAF|KCVG 231051Z 231212 12012KT 4SM -RA BR OVC008|WS005/27050KT TEMPO 1719 1/2SM -RA FG|FM1930 09012KT 1SM -DZ BR VV003 BECMG 2021 5SM HZ=
500 feet AGL from 270° at 50 KT.
What is meant by the entry in the remarks section of METAR surface report for KBNA?|METAR KBNA 211250Z 33018KT 290V260 1/2SM R31/2700FT +SN|BLSNFG VV008 00/M03 A2991 RMK RAE42SNB42
Rain ended 42 past the hour, snow began 42 past the hour.
The Surface Analysis Chart depicts
actual frontal positions, pressure patterns, temperature, dew point, wind, weather, and obstructions to vision at the valid time of the chart.
The Low-Level Significant Weather Prognostic Chart depicts weather conditions
that are forecast to exist at a valid time shown on the chart.
Which meteorological conditions are depicted by a prognostic chart?
Conditions forecast to exist at a specific time shown on the chart.
What information is provided by a Convective Outlook (AC)?
It provides prospects of both general and severe thunderstorm activity during the following 24 hours.
A planned low altitude flight from northern Florida to southern Florida at 00Z is likely to encounter
showery precipitation, thunderstorms/rain showers covering half or more of the area.
Interpret this PIREP.|MRB UA/OV MRB/TM1430/FL060/TPC182/SK BKN BL/WX RA/TB MDT
At 6,000 feet; between layers; moderate turbulence; moderate rain.
What weather conditions are depicted within the area indicated by arrow E?
Occasional cumulonimbus, 1/8 to 4/8 coverage, bases below 24,000 feet MSL, and tops at 40,000 feet MSL.
What weather conditions are depicted within the area indicated by arrow D?
Forecast isolated embedded cumulonimbus clouds with tops at 43,000 feet MSL, and less than 1/8 coverage.
Which weather forecast describes prospects for an area coverage of both severe and general thunderstorms during the following 24 hours?
Convective Outlook.
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.
What weather conditions are depicted in the area indicated by arrow A on the Radar Summary Chart?
Strong to very strong echoes; echo tops 30,000 feet MSL; thunderstorms and rain showers.
What weather conditions are depicted in the area indicated by arrow D on the Radar Summary Chart?
Intense to extreme echoes within the smallest contour, echo tops 29,000 feet MSL, and cell movement toward the northeast at 50 knots.
For most effective use of the Radar Summary Chart during preflight planning, a pilot should
compare it with the charts, reports, and forecasts of a three-dimensional picture of clouds and precipitation.
The Severe Weather Outlook Chart, which is used primarily for advance planning, provides what information?
A 24-hour severe weather outlook for possible thunderstorm activity.
Using the DAY 2 CONVECTIVE OUTLOOK, what type of thunderstorms, if any, may be encountered on a flight from Montana to central California?
The Hazardous Inflight Weather Advisory Service (HIWAS) is a continuous broadcast over selected VORs of
SIGMETs, CONVECTIVE SIGMETs, AIRMETs, Severe Weather Forecasts Alerts (FAA No: AWW), and Center Weather Advisories.
What is the maximum wind velocity forecast in the jet stream shown on the high level Significant Weather Prognostic Chart over Canada?
What is the height of the Tropopause over Kentucky?
What is the approximate wind direction and velocity at 34,000 feet (see arrow C)?
290°/50 knots.
What is the approximate wind direction and velocity at CVG at 34,000 feet (see arrow A)?
230°/35 knots.
AIRMET's are issued on a scheduled basis every
six hours.
On what frequency should you obtain En Route Flight Advisory Service below FL 180?
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