Thunderstorms Flashcards
What are the development stages of a thunderstorm?
Cumulus, Mature and Dissipating.
Explain Updraft phase of the Cumulus stage.
Updraft: Small convective clouds merge and grow into a convective cell. Only updrafts are present and they draw air into the base/ sides of cloud.
Base of cumulus: Up to 4000 ft.
Height: Over 20 000ft.
Updraft Speed: 3000 ft/min
Explain Updraft phase of mature stage.
Rain at earth’s surface indicates the mature stage.
Cloud continues to grow, updrafts reach max speed of 6000 ft/min.
Cloud reaches tropopause, possibly stratosphere if updraft strong enough. As a result, an anvil shape of cloud may form.
Explain the Down/ Microburst phase of the Mature Stage.
Exceptionally violent winds that last for a few minutes, only about a mile across.
Originate out of downdrafts that flow out and away from storm.
Which thunderstorms do hail exist in?
All thunderstorms.
Where does hail develop and exist?
Develops and exists between 10 000 and 30 000ft.
What is the distance hail can be thrown?
Up to five miles ahead of storm, originating in the clear air under the anvil.
What causes a roll cloud?
The cool outflow that slides under the warm inflow.
What must occur side by side for lightning to occur?
Strong up and down drafts.
What must move up and down in the drafts for lightning to form?
Water droplets, hail and snow.
What’s the differences/ similarities between a funnel cloud and a tornado?
Tornado contacts ground, funnel cloud hangs down from cloud.
Both are violent rotating columns of air descending from a thunderstorm.
In which quadrant of a TS does a tornado exist?
1) SW
2) NE
3) NW
4) SE
SW
State position (ahead, below or behind) of the Gust front, a microburst and a tornado.
Gust front: Ahead of storm
Microburst: Below or just ahead of storm
Tornado: Behind storm
What happens towards the end of the Mature stage with regards to up/ down drafts?
Up draft weakens until entire cell comprises of downdrafts.
What are the types of frontal thunderstorms?
Warm frontal, cold frontal, trowal and squall line.
Which type of frontal TS is least and which is most severe?
Warm front: Least severe
Squall Line: Most severe (may contain hail, destructive winds and tornadoes.)
Which type of frontal TS moves away from front?
Squall line
Formation in a warm, moist air mass, in no way associated with a front and typically isolated or widely scattered indicates which type of thunderstorms?
Air mass thunderstorms.
Formation in a warm, moist air mass, in no way associated with a front and typically isolated or widely scattered indicates which type of thunderstorms?
Air mass thunderstorms.
What are the types of Air Mass TS?
Convective, Orographic and Nocturnal.
What is the most common hazard associated with TS?
Turbulence
If a TS has more lightning, does it have more or less turbulence?
More turbulence
Radar weather avoidance of a TS requires what distance for:
a) Flying below the freezing level
b) Flying above the freezing level
c) Flying above 30 000 ft.
a) 5 miles
b) 10 miles
c) 20 miles.
As a general rule, how high should you clear the top of a TS for every 10 kts of wind speed at cloud top level?
a) 500 ft
b) 1000 ft
c) 2500 ft
d) 3000 ft
1000 ft
During approach and landing heavy rain can cause loss of lift due to roughening if the upper wing surface. What else can it do?
Reduce visibility and cause hydroplaning during landing.
Not all water in a TS falls to earth, can suspended raindrops be dangerous to the aircraft?
Yes, they can do as much damage as hail.
The heaviest icing conditions in a TS are found where? And why?
Just above freezing level due to largest concentration of super-cooled water droplets.
What does a Gust Front result in regarding wind, temp and pressure?
Change in wind speed/ direction, sharp cooling and pressure rise.
Where is the gust front strongest? How far can it extend beyond a TS?
Ahead of TS and 10 - 15 miles ahead.
What is a gust front indicator?
Shelf clouds that form near leading edge.
The possibility of a lightning strike on aircraft ______ with ______ aircraft size.
[increase(s)(d) or decrease(s)(d)]
Increases and increased
What are the two types of lightning?
Triggered and Natural.
Which type of lightning is associated with static charge?
Triggered
Which type of lightning is associated with strong radar returns?
Natural lightning
Explain the pressure variations as a TS approaches, moves overhead and moves on.
Abrupt fall on approach
Abrupt rise when overhead
Gradual return as it moves on
