Questions and Answers
Convective clouds which penetrate a stratus layer can produce which threat to instrument flight?
Which weather phenomenon signals the beginning of the mature stage of a thunderstorm?
The start of rain at the surface.
During the life cycle of a thunderstorm, which stage is characterized predominantly by downdrafts?
Dissipating.
What feature is normally associated with the cumulus stage of a thunderstorm?
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What is indicated by the term 'embedded thunderstorms'?
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Which type of cloud is associated with violent turbulence and a tendency toward the production of funnel clouds?
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Where do squall lines most often develop?
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Where can the maximum hazard zone caused by wind shear associated with a thunderstorm be found?
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Atmospheric pressure changes due to a thunderstorm will be at the lowest value when?
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Why are downdrafts in a mature thunderstorm hazardous?
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What is a difference between an air mass thunderstorm and a steady-state thunderstorm?
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Which type of storms are most likely to produce funnel clouds or tornadoes?
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A clear area in a line of thunderstorm echoes on a radar scope indicates?
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When flying over the top of a severe thunderstorm, the cloud should be overflown by at least?
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Which weather condition is an example of a nonfrontal instability band?
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A steady state thunderstorm is associated with?
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Shear turbulence from a thunderstorm has been encountered?
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Intense radar storm echoes should be avoided by a margin of?
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Downdrafts in thunderstorms can be expected to exceed?
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Storm gust fronts often move as much as?
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A thunderstorm first begins when?
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Downdrafts in a thunderstorm may exceed?
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Study Notes
Thunderstorms Overview
- Embedded thunderstorms can pose a significant threat to instrument flight, especially when they occur within stratiform clouds.
- The onset of rain at the surface signals the transition into the mature stage of a thunderstorm.
Thunderstorm Life Cycle
- The dissipating stage is dominated by downdrafts, leading to weakening storm intensity.
- During the cumulus stage, a continuous updraft is present, forming the initial structure of the storm.
Thunderstorm Definitions
- "Embedded thunderstorms" refer to storms obscured by other cloud types, making them less visible to pilots.
- Cumulonimbus mamma clouds are associated with severe turbulence and have the potential to form funnel clouds.
Development and Hazards
- Squall lines typically develop ahead of cold fronts, bringing severe weather.
- Wind shear poses a maximum hazard zone on all sides of the thunderstorm and directly beneath it.
Atmospheric Effects
- Atmospheric pressure reaches its lowest point as a thunderstorm approaches.
- Downdrafts in mature thunderstorms pose hazards due to being cooled by rain, increasing their downward velocity.
Thunderstorm Types
- Air mass thunderstorms differ from steady-state thunderstorms as they often experience downdrafts that can interrupt updrafts.
- Cold front and squall line thunderstorms are most likely to develop funnel clouds or tornadoes.
Radar and Flight Safety
- Clear areas on radar, showing no precipitation, indicate pockets where storm echoes are absent.
- When flying over severe thunderstorms, maintain a vertical clearance of at least 1,000 feet for every 10 knots of windspeed.
Storm Characteristics
- Nonfrontal instability bands, such as squall lines, can lead to severe weather.
- Steady-state thunderstorms are primarily linked to broader weather systems.
Turbulence and Distance
- Shear turbulence can be felt from a significant distance, up to 20 miles away from the severe thunderstorm.
- It is advisable to avoid intense radar storm echoes by a margin of 20 nautical miles.
Downdraft Intensities
- Downdrafts can reach speeds exceeding 2,500 feet per minute and may surpass 24 knots.
- Storm gust fronts can extend 15 miles ahead of the associated precipitation.
Storm Formation
- The initiation of a thunderstorm occurs when lifting forces elevate cooler air, promoting upward movement and cloud formation.
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Description
This quiz covers the essential aspects of thunderstorms, including their life cycle stages, definitions of different types, and the associated hazards for flight operations. Understand the complexities of embedded thunderstorms and the impacts of squall lines and wind shear. Perfect for aviation enthusiasts and professionals looking to enhance their knowledge.