Weather Flashcards
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
What prevents air from flowing directly from high-pressure areas to low-pressure areas?
Coriolis force
Moisture is added to air by
Evaporation and sublimation
Ice pellets encountered during flight normally are evidence that
A warm front is about to pass
What is the convergence of temperature and dewpoint rate?
2.45°C or 4.4°F
Fog produced by frontal activity is a result of saturation due to
evaporation of precipitation
Which in-flight hazard is most commonly associated with warm fronts?
Precipitation-induced fog
During preflight preparation, weather report forecasts which are not routinely available at the local service outlet (AFSS) can best be obtained by means of contacting
weather forecast office (WFO)
The Telephone Information Briefing Service (TIBS) provided by AFSSs includes
continuous recording of meteorological and/or aeronautical information available by telephone.
What wind conditions would you anticipate when squalls are reported at your destination?
Sudden increases in windspeed of at least 16 knots to a sustained speed of 22 knots or more for at least 1 minute.
Terminal Aerodrome Forecasts (TAF) are issued how many times a day and cover what period of time?
Four times daily and are usually valid for a 24 hour period.
Which information section is contained in the Aviation Area Forecast (FA)?
VFR Clouds and Weather (VFR CLDS/WX)
The section of the Aviation Area Forecast (FA) entitled VFR Clouds and Weather contains a summary of
sky condition, cloud heights, visibility, obstructions to vision, precipitation, and sustained surface winds of 20 knots or greater
What values are used for Winds Aloft Forecasts?
True direction and knots
Which chart provides a ready means of locating observed frontal positions and pressure centers?
Surface Analysis Chart
The Surface Analysis Chart depicts
actual frontal positions pressure patterns temperature dewpoint wind weather obstructions to vision
…at the valid time of the chart
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
Hatching on a Constant Pressure Analysis Chart indicates
windspeeds 70 knots to 110 knots
What flight planning information can a pilot derive from Constant Pressure Analysis Charts?
Winds and temperatures aloft
The minimum vertical wind shear value critical for probable moderate or greater turbulence is
6 knots per 1,000 feet
A strong wind shear can be expected on what side of a jet stream core and at what speed?
on the low-pressure side of a jetstream core where the speed at the core is stronger than 110 knots
One of the most dangerous features of mountain waves is the turbulent areas in and
below rotor clouds
Weather Advisory Broadcasts, including Severe Weather Forecast Alerts (AWWW), Convective SIGMETs, and SIGMETs, are provided by
Air Route Traffic Control Centers (ARTCC)
The National Convective Weather Forecast is a supplement to, but does not substitute for, the report and forecast contained in
Convective SIGMETs
You are obtaining a weather briefing for a xc flight. The briefer has given you a convective outlook for your route of flight. What are the three levels of convective activity (not turbulence) in the convective outlook?
Slight, Moderate, High
Decode the radar weather report:
KOKC 1934 LN8TRW++/+ 86/40 164/60 199/115 15W C2425 MT 570 AT159/65 2 INCH HAIL RPRTD THIS CELL
KOKC 1934 LN8TRW++/+ 86/40 164/60 199/115 15W C2425 MT 570 AT159/65 2 INCH HAIL RPRTD THIS CELL
for KOKC at 1934Z, area of echos 8/10 coverage, very heavy rain showers, area defined by 86 degrees at 40NM, 164 degrees at 60NM, and 199 degrees at 115NM, area 15NM wide, movement from 240 degrees at 25 knots, maximum tops 57,000 feet located at 159 degrees at 65NM, and 2 inch hail.
How long is the forecast of a Convective SIGMET valid for?
2 hours
What weather phenomenon is implied within an area enclosed by bold yellow dashed lines on a US High-Level Significant Weather Prognostic Chart?
Moderate or severe turbulence
What are some weather indications of the imminent passage of a cold front?
High dew point, falling barometric pressure
What weather phenomena can be expected before the passage of an occluded front?
Precipitation and poor visibility
If the temperature lapse rate decreases, what happens to the stability of the air?
Stability increases
What significant cloud coverage is reported by this pilot report?
KMOB UA/OV 15NW 1340Z/SK 025 OVC 045/075 OVC 080/090 OVC
A) Three (3) separate overcast layers exist with bases at 2,500, 7,500, and 9,000 feet.
B) The top of the lower overcast is 2,500 feet; base and top of second overcast layer is 4,500 and 7,500 feet, respectively.
C) The base of the second overcast layer is 2,500 feet; top of the second overcast layer is 7,500 feet; base of third layer is 9,000 feet.
A) Three (3) separate overcast layers exist with bases at 2,500, 7,500, and 9,000 feet.
What is the approximate base of the cumulus clouds if the temperature at 2,000 feet MSL is 10°C and the dewpoint is 1°C?
A) 3,000 feet MSL
B) 4,000 feet MSL
C) 6,000 feet MSL
C) 6,000 feet MSL
Temp/Dewpoint spread is 9°C
9°C / 2.45 = 3.67 * 1000 = 3670
3670 + 2000 (surface in MSL) = 5670 ~ 6000 feet MSL
The Aviation Weather Center (AWC) prepares FA’s for the contiguous US how often?
three times a day
Which forecast provides specific information concerning expected sky cover, cloud tops, visibility, weather, and obstructions to vision in a route format?
Area Forecast
What weather phenomenon is implied within an area enclosed by red scalloped lines on a US High-Level Significant Weather Prognostic Chart?
Moderate or severe icing
From what weather chart can the observed temperature, wind, and temperature/dewpoint spread be determined at a specified altitude?
Constant Pressure Analysis Chart
The National Convective Weather Forecast is a supplement to, but does not substitute for, the report and forecast information contained in
Convective SIGMETs
What are some weather indications of the imminent passage of a cold front?
High dewpoint, falling barometric pressure
If ice pellets are falling while you are performing your preflight inspection, what does this indicate?
an inversion is taking place
When and where is the jet stream the strongest?
Northern and Southern Hemispheres winters
