CAX Written - Weather
When total sky cover is few or scattered, the height shown on the Weather Depiction Chart is the
base of the lowest layer
One of the most dangerous features of mountain waves is the turbulent areas in and
below rotor clouds
The Low Level Wind Shear Alert System (LLWAS) provides wind data and software process to detect the presence of a
change in wind direction and/or speed within a very short distance above the airport
Turbulence that is encountered above 15,000 ft AGL not associated with cumuliform cloudiness, including thunderstorms, should be reported as
clear air turbulence
With regard to windflow patterns shown on surface analysis charts; when the isobars are
close together, the pressure gradient force is greater and wind velocities are stronger
The Hazardous Inflight Weather Advisor Service (HIWAS) is a broadcast service over selected VORs that provides
continuous broadcasts of in-flight weather advisories
The Telephone Information Briefing Service (TIBS) provided by AFSSs includes
continuous recording of metrological and/or aeronautical information available by telephone
A moist, unstable air mass is characterized by
cumuliform clouds and showery precipitation
Hail is most likely to be associated with
cumulonimbus clouds
Which is true regarding actual air temperature and dew point temperatures spread? The temperature spread
deceases as the relative humidity increases
When flying low over hilly terrain, ridges, or mountain ranges, the greatest potential danger form turbulent air currents will usually be encountered on the
downwind side when flying into the wind
Moisture is added to air by
evaporation and sublimation
Fog produced by frontal activity is a result of saturation due to
evaporation of precipitation
The most dangerous hazards operating in the vicinity fo thunderstorms are
hail and turbulence
A common location of clear air turbulence is
in an upper trough on the polar side of a jet stream
Hazardous wind shear is commonly encountered
in areas of temperature inversion and near thunderstorms
If there is a low pressure en route during your flight, what can you expect?
increasing clouds and precip
Which is true regarding a cold front occlusion? The air ahead of the warm front
is warmer than the air behind the overtaking cold front
On a surface analysis chart, the solid lines that depict sea level pressure patterns are called
isobars
When flying into a low-pressure area in the Northern Hemisphere, the wind direction and velocity will be from the
left and increasing
The difference found by subtracting the temperature of a parcel of air theoretically lifted from the surface to 500 millibars and the existing temperature at 500 millibars is called the
lifted index
Convective currents are most active on warm summer afternoons when winds are
light
A pilot reporting turbulence that momentarily causes slight, erratic changes in altitude and/or attitude should report it as
light turbulence
The jet stream and associated clear air turbulence can sometimes be visually identified in flight by
long streaks of cirrus clouds
When turbulence causes changes in altitude and/or attitude but aircraft control remains positive, that should be reported as
moderate
Which situation would most likely result in freezing precipitation? Rain falling from air which has a temperature of
more than 0C into air having a temperature of 0C or less
A freezing level panel of the composite moisture stability chart is an analysis of
observed freezing level data from upper air observations
A strong wind shear can be expected
on the low-pressure side of a jet stream core where the speed at the core is stronger than 110 knots.
The general circulation of air associated with a high-pressure area in the Northern Hemisphere is
outward, downward, and clockwise
To best determine observed weather conditions between weather reporting stations, the pilot should refer to
pilot reports
During an approach, the most important and most easily recognized means of being alerted to possible wind shear is monitoring the
power and vertical velocity required to remain on the proper glidepath
Which in-flight hazard is most commonly associated with warm fronts?
precipitation-induced fog
In the Northern Hemisphere, the wind is deflected to the
right by Coriollis Force
The section of the Aviation Area Forecast (FA) entitled VFR Clouds and Weather contains a summary of
sky condition, cloud height, visibility, obstruction to vision, precipitation, and sustained surface winds of 20 knots or greater
If you find yourself in convective weather with severe turbulence, you should
slow below maneuvering speed (Va) or manufacturer's recommended turbulence airspeed, maintain wings level, and accept airspeed and altitude deviations.
During the winter months in the middle latitudes, the jet stream shifts toward the
south and speed increases
The most severe weather conditions, such as destructive winds, heavy hail, and tornadoes, are generally associated with
squall lines
The formation of either predominantly stratiform or predominantly cumuliform clouds is dependent upon the
stability of the air being lifted.
The conditions necessary for the formation of stratiform clouds are a lifting action and
stable, moist air
If clouds form as a result of very stable, moist air being forces to ascend a mountain slope, the clouds will be
stratus type with little vertical development and little or no turbelence
Virga is best described as
streamers of precipitation trailing beneath clouds which evaporates before reaching the ground
On a Surface Analysis Chart, close spacing of the isobars indicates
strong pressure gradient
Frost covering the upper surface of an airplane wing usually will cause
the airplane to stall at an angle of attack that is lower than normal
Low-level wind shear may occur when
there is a low-level temperature inversion with strong winds above the inversion
The Aviation Weather Center (AWC) prepares FA's for the contiguous U.S.
three times each day
SIGMET's are issued as a warning of weather conditions which are hazardous
to all aircraft
The conditions necessary for the formation of cumulonimbus clouds are a lifting action and
unstable, moist air
The presence of standing lenticular altocumulus clouds is a good indication of
very strong turbulence
Dashed lines on a Surface Analysis Chart, if depicted, indicate that the pressure gradient is
weak
The strength and location of the jet stream is normally
weaker and farther north in the summer
Which weather chart depicts conditions forecast to exist at a specific time in the future?
12-hour Significant Weather Prognostication Chart
What are the standard temperature and pressure values for sea level?
15 C and 29.92 Hg
How long is the forecast of a Convective SIGMET valid for
2 hours
What is the minimum distance should exist between intense radar echoes before any attempt is made to fly between these two thunderstorms?
4o miles
The visibility entry in a TAF of P6SM implies that the prevailing visibility is expected to be greater than
6 Statute miles
The minimum vertical wind shear value critical for probable moderate of greater turbulence is
6 kts per 1000 ft
What is the approximate base of the cumulus clouds if the temperature at 2,000 ft MSL is 10 deg C and the dew point is 1 C
6000 ft MSL
Which type of jet stream can be expected to cause the greater turbulence?
A curving jet stream associated with a deep low-pressure trough
Which is true with respect to a high- or low-pressure system?
A high-pressure area or ridge is an area of descending air.
Which forecast provides specific information concerning expected sky cover, cloud tops, visibility, weather, and obstructions to vision in a route format?
Area Forecast
During preflight planning, weather report forecasts which are not routinely available at the local service outlets (AFSS) can best be obtained by mean of contacting
weather forecast office (WFO)
What prevents air from flowing directly from high-pressure areas to low-pressure areas?
Coriolis force
Why does the wind have a tendency to flow parallel to the isobars above the friction level?
Coriolis force tends to counterbalance the horizontal pressure gradient
Which are characteristics of a cold air mass moving over a warm surface?
Cumuliform clouds, turbulence, and good visibility
What visible signs indicate extreme turbulence in thunderstorms?
Cumulonimbus clouds, very frequent lightning, and roll clouds
What are the stages in the lift cycle of a thunderstorm?
Cumulus stage, Mature stage and Dissipating stag
During the life cycle of a thunderstorm, which stage is characterized predominately by downdrafts?
Dissipating
If a temperature inversion is encountered immediately after takeoff or during an approach to a landing, a potential hazard exists due to
wind shear
Hatching on a Constant Pressure Analysis Chart indicates
windspeeds 70 kts to 110 kts
What is the standard temperature at 20,000 ft
-25 deg C
What is the standard temperature at 10,000 ft
-5 deg C
If airborne radar is indicating an extremely intense thunderstorm echo, this thunderstorm should be avoided by a distance of at least
20 miles
What is the upper limit of the Low level Significant Weather Prognostic Chart?
24,000 Ft
The U.S. High-Level Significant Weather Prognostic Chart forecasts significant weather for what airspace?
25,000 ft to 63,000 ft
To determine pressure altitude prior to takeoff, the altimeter should be set to
29.92" Hg and the altimeter indication noted
Which is true regarding high- or low-pressure system?
A low-pressure area or trough is an area of rising air
The most current enroute and destination weather information for an instrument flight should be obtained from the
AFSS
What type of Inflight Weather Advisories provides an en route pilot with information regarding the possibility of moderate icing moderate turbulence, winds of 30 knots or more at the surface and extensive mountain obscurement?
AIRMETs and Center Weather Advisories (CWA)
Which feature is associated with the tropopause?
Abrupt change in temperature lapse rate
Weather Advisory Broadcasts, including Severe Weather Forecasts Alerts (AWW), Convective SIGMET's, and SIGMET's are provided by
Air Route Traffic Control Centers (ARTCC)
Which conditions are favorable for the formation of a surface based temperature inversion?
Clear, cool nights with calm or light wind
From which of the following can the observed temperature, wind, and temperature/dewpoint spread be determined at a specified altitude?
Constant Pressure Analysis Charts
Which is a characteristic typical of a stable air mass?
Continuous precipitation
What feature is normally associated with the cumulus stage of a thunderstorm
Continuous updraft
The National Convective Weather Forecast is a supplement to, but does not substitute for, the report and forecast information contained in
Convective SIGMETs.
Which would increase the stability of an air mass?
Cooling from below
In-Flight Aviation Advisories include what type of information?
Forecasts for potentially hazardous flying conditions for enroute aircraft
TAF are issued how many times a day and cover what period of time?
Four times daily and usually valid for a 24 hr period
What is indicated if ice pellets are encountered at 8,000 ft?
Freezing rain at higher altitudes
Which statement is true concerning the hazards of hail?
Hailstorms may be encountered in clear air several miles from a thunderstorm
You are planning a XC flight across the US. The flight will be divided into several segments. For flight planning, time en route fuel requirements are air circulation are essential. In which direction does the air circulate around a low in the Northern Hemisphere?
In the Northern Hemisphere, the air in an area around a low is deflected to the right and circulates counter clockwise
What single reference contains information regarding expected volcanic eruption, that is occurring or is expected to occur?
In-Flight Weather Advisories
With respect to advection fog, which statement is true?
It can appear suddenly during day or night, and it is more persistent than radiation fog
What is an important characteristic of wind shear?
It can be present at any level and can exist in both a horizontal and vertical direction
What information is provided by the Radar Summary Chart that is not shown on the other weather charts?
Lines and cells of hazardous thunderstorms
What weather phenomenon is implied within an area enclosed by red scalloped line on a U.S. High-Level Significant Weather Prognostic Chart?
Moderate or severe icing
What weather phenomenon is implied within an area enclosed by bold yellow dashed lines on a US High-Level Signifiant Weather Prognostic Chart?
Moderate or severe turbulence
Of the following, which is accurate regarding turbulence associated with thunderstorms?
Outside the cloud, shear turbulence can be encountered 20 miles laterally from a severe storm.
What are the characteristics of stable air?
Poor visibility, Steady precipitation and stratus clouds
What causes wind?
Pressure differences
In what ways do advection fog, radiation fog, and steam fog differ in their formation or location?
Radiation fog is restricted to land areas; advection fog is the most common along coastal areas; steam fog forms over a water surface
What is the characteristic of stable air
Restricted visibility
You are planning a trip for the following day. Which weather chart would be most appropriate for determining frontal locations along your intensed route at the time of your flight/
Significant Weather Prog Chart
You are obtaining a weather briefing for a cross country flight. The briefer has given you a convective outlook for you route of flight. What are the three levels of convective activity in the convective outlook?
Slight, Moderate and High
When an air mass is stable, which of these conditions are most likely to exist?
Smoke, dust, haze, etc., concentrated at the lower levels with resulting poor visibility
What is a characteristic of stable air?
Stratiform Clouds
What type weather can one expect from moist, unstable air, and very warm surfaces temperatures?
Strong updrafts and cumulonimbus clouds
When conditionally unstable air with high-moisture content and very warm surface temperature is forecast, one can expect what type of weather?
Strong updrafts and cumulonimbus clouds
What wind conditions would you anticipate when squalls are reported at your destination?
Sudden increase in windspeed of at least 16 knots to a sustained speed of 22 kts or more for at least 1 minute
Which chart provides a ready means of locating observed frontal positions and pressure centers?
Surface Analysis Chart
What lifts advection fog into a low stratus clouds?
Surface winds of approx. 15 knots o rstronger
From which measurements of the atmosphere can stability be determined?
The ambient lapse rate
Select the true statement pertaining to the life cycle of a thunderstorm
The beginning of rain at the Earth's surface indicates the mature stage of the thunderstorm
Ice pellets encountered during flight normally are evidence that
a warm front is about to pass
Which is true regarding the use of airborne weather-avoidance radar for the recognition of certain weather conditions?
The radarscope provides no assurance of avoiding instrument weather conditions
What determines the structure or type of clouds which will form as a result of air being forced to ascend?
The stability of the air before lifting occurs
Which weather phenomenon signals the beginning of the mature stage of a thunderstorm
The start of rain
Which statement is true regarding squall lines?
They are nonfrontal and often contain severe, steady-state thunderstorms
Which correctly describes the purpose of Convective SIGMET's (WST)?
They consist of either an observation and a forecast or just a forecast for tornadoes, significant thunderstorm activity, or hail greater than or equal to 3/4in in diameter
Which statement is true concerning squall lines?
They offer the most intense weather hazards to aircraft
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
Which cloud types would indicate convective turbulence?
Towering cumulus clouds
What values are used for Winds Aloft Forecasts?
True Direction and Knots
Which combination of weather-producing variables would likely result in cumuliform-type clouds, good visibility and showery rain?
Unstable, moist air and orographic lifting.
Which information section is contained in the Aviation Area Forecast (FA)?
VFR Clouds and Weather (VFR CLDS/WX)
A situation most conducive to the formation of advection fog is
an air mass moving inland from the coastline during the winter
Which would decrease the stability of an air mass?
Warming from below
Which provides a graphic display of both VFR and IFR weather?
Weather Depiction Chart
Advection fog as drifted over a coastal airport during the day. What may tend to dissipate or lift this fog into a low stratus clouds?
Wind 15 knots or stronger
What does the contraction VRB in the Terminal Aerodrome Forecast (TAF) mean?
Wind direction is variable
What flight planning information can a pilot derive from Constant Pressure Analysis Charts?
Winds and temperature aloft
While flying cross country, in the Northern Hemisphere, you experience a continuous left crosswind which is associated with a major wind system. This indicates that you
are flying toward an area of generally unfavorable weather conditions
The wind system associated with a low-pressure area in the Northern Hemisphere is
a cyclone and is caused by Coriolis force
Every physical process of weather is accompanied by or is the result of
a heat exchange.
During departure, under conditions of suspected low-level wind shear, a sudden decrease in headwind will cause
a loss in airspeed equal to the decrease in wind velocity