Thunderstorm Overview and Hazards

Questions and Answers

Convective clouds which penetrate a stratus layer can produce which threat to instrument flight?

Turbulence

Embedded thunderstorms (correct)

Clear air turbulence

Fog

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?

Continuous updraft. Signup and view all the answers

What is indicated by the term 'embedded thunderstorms'?

Thunderstorms are obscured by other types of clouds. Signup and view all the answers

Which type of cloud is associated with violent turbulence and a tendency toward the production of funnel clouds?

Cumulonimbus mamma. Signup and view all the answers

Where do squall lines most often develop?

Ahead of a cold front. Signup and view all the answers

Where can the maximum hazard zone caused by wind shear associated with a thunderstorm be found?

On all sides and directly under the thunderstorm cell. Signup and view all the answers

Atmospheric pressure changes due to a thunderstorm will be at the lowest value when?

When the thunderstorm is approaching. Signup and view all the answers

Why are downdrafts in a mature thunderstorm hazardous?

Downdrafts are kept cool by cold rain which tends to accelerate the downward velocity. Signup and view all the answers

What is a difference between an air mass thunderstorm and a steady-state thunderstorm?

Air mass thunderstorm downdrafts and precipitation retard and reverse the updrafts. Signup and view all the answers

Which type of storms are most likely to produce funnel clouds or tornadoes?

Cold front or squall line thunderstorms. Signup and view all the answers

A clear area in a line of thunderstorm echoes on a radar scope indicates?

An area where precipitation drops are not detected. Signup and view all the answers

When flying over the top of a severe thunderstorm, the cloud should be overflown by at least?

1,000 feet for each 10 knots windspeed. Signup and view all the answers

Which weather condition is an example of a nonfrontal instability band?

Squall line. Signup and view all the answers

A steady state thunderstorm is associated with?

Weather systems. Signup and view all the answers

Shear turbulence from a thunderstorm has been encountered?

20 miles from the severe thunderstorm. Signup and view all the answers

Intense radar storm echoes should be avoided by a margin of?

20 nm. Signup and view all the answers

Downdrafts in thunderstorms can be expected to exceed?

2,500 feet per minute. Signup and view all the answers

Storm gust fronts often move as much as?

15 miles ahead of the associated precipitation. Signup and view all the answers

A thunderstorm first begins when?

Lifting forces carry cooler air inward and upward. Signup and view all the answers

Downdrafts in a thunderstorm may exceed?

24 knots. Signup and view all the answers

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.