SU7: Weather Flashcards
What information is contained in a CONVECTIVE SIGMET?
Tornadoes, embedded thunderstorms, and hail 3/4 inch or greater in diameter.
SIGMETs are issued as a warning of weather conditions hazardous to which aircraft?
All Aircraft.
SIGMETS (Significant meteorological Information) warn of weather considered potentially hazardous to all aircraft.
SIGMET advisories cover severe and extreme turbulence; severe icing; and widespread duststorms, sandstorms, or volcanic ash that reduce visibility to less than 3SM.
During the life cycle of a thunderstorm, which stage is characterized predominately by downdrafts?
Dissipating.
(AC 00-6B Chap 19) ( ? )
Thunderstorms have three life cycles: cumulus, mature, and dissipating. It is in the dissipating stage that the storm is characterized by downdrafts as the storm rains itself out.
In which situation is advection fog most likely to form?
A. A warm, moist air mass on the windward side of mountains.
B. An air mass moving inland from the coast in winter.
C. A light breeze blowing colder air out to sea.
B. An air mass moving inland from the coast in winter.
Answer (B) is correct. (AC 00-6B Chap 16) ( ? )
Advection fog forms when moist air moves over colder ground or water. It is most common in coastal areas.
Low-level turbulence can occur and icing can become hazardous in which type of fog?
A. Upslope fog.
B. Steam fog.
C. Rain-induced fog.
B. Steam fog.
Answer (B) is correct. (AC 00-6B Chap 16) ( ? )
Steam fog forms in winter when cold, dry air passes from land areas over comparatively warm ocean waters and is composed entirely of water droplets that often freeze quickly. Low-level turbulence can occur, and icing can become hazardous.
The suffix “nimbus,” used in naming clouds, means
a rain cloud.
AC 00-6B Chap 13) ( ?
The suffix “nimbus” or the prefix “nimbo” means a rain cloud.
A pilot can expect a wind-shear zone in a temperature inversion whenever the wind speed at 2,000 to 4,000 feet above the surface is at least
A. 25 knots.
B. 10 knots.
C. 15 knots.
A. 25 knots.
Answer (A) is correct. (AC 00-6B Chap 17) ( ? )
When taking off or landing in calm wind under clear skies within a few hours before or after sunset, prepare for a temperature inversion near the ground. You can be relatively certain of a shear zone in the inversion if you know the wind is 25 kt. or more at 2,000 to 4,000 feet. Allow a margin of airspeed above normal climb or approach speed to alleviate the danger of stall in the event of turbulence or sudden change in wind velocity.
How are significant weather prognostic charts best used by a pilot?
A. For determining areas to avoid (freezing levels and turbulence).
B. For overall planning at all altitudes.
C. For analyzing current frontal activity and cloud coverage.
A. For determining areas to avoid (freezing levels and turbulence).
Answer (A) is correct. (AC 00-45H Chap 5) ( ? )
Weather prognostic charts forecast conditions that exist 12 and 24 hr. in the future. They include two types of forecasts: low level significant weather, such as IFR and marginal VFR areas, and moderate or greater turbulence areas and freezing levels.
What measurement can be used to determine the stability of the atmosphere?
A. Actual lapse rate.
B. Surface temperature.
C. Atmospheric pressure.
A. Actual lapse rate.
Answer (A) is correct. (AC 00-6B Chap 12) ( ? )
Atmospheric stability is determined by vertical movements of air. Warm air rises when the air above is cooler. The actual lapse rate, which is the decrease of temperature with altitude, is therefore a measure of stability.
Thunderstorms which generally produce the most intense hazard to aircraft are
squall line thunderstorms.
A squall line is a nonfrontal, narrow band of active thunderstorms. It often contains severe, steady-state thunderstorms and presents the single most intense weather hazard to aircraft.
