Thunderstorm and Severe Weather Quiz Flashcards
What are the types of hazards result from severe weather
- Flooding
- Lightning
- Winds (and microbursts)
- Hail
- Tornadoes
Definition
Thunderstorm
A storm that generates lightning and thunder
Definition
Air-Mass Thunderstorm
Forms in a warm, moist, unstable air mass
- Most frequent in the afternoon in spring and summer
Definition
Organized Thunderstorms
Form by frontal activity, upper level support (jet stream), steep lapse rates, etc
- Produce majority of severe weather
What stages do thunderstorms go through in their life cycle
- Cumulus stage
- Mature stage
- Dissipation stage
Definition
Entrainment
Pull of cool, dry air into the cloud - intersifies the downdraft by aiding evaporation and cooling
Definition
Most Active Period
Gusty winds, lightning, heavy precipitation, small hail, etc.
Influencing Factors of Flooding
- Rainfall intensity and duration
- Surface conditions
- Topography
Cumulus Stage
Clouds continute to grow vertically and form a cumulus tower
- Dominated by updrafts
How does Cumulus Stage form
Require moist air and the release of latent heat
Mature Stage
Falling precipitaiton causes drag on air and initiates downdrafts
Dissipating Stage
- Downdrafts and entrainment being to dominate
- Updrafts weaken and supply of moisture is cutoff
- Cloud beings to evaporate
Thunderstorm Occurrence and Growth
Air mass thunderstorms formed in high surface temps and unequal heating
- Mountainous regions have the most air-mass thunderstorms
What can triggered thunderstorms
- Convergence from sea to land airflow
- Convergence and frontal wedging associated with mid-latitude cyclones
- Convergence along the ITCZ
Severe Thunderstorm
A thunderstorm containing one or more of the following (NOAA)
- Winds > 58mph
- Hail > .75 in
- Tornado
Gust Front
Boundary separating cold downdraft and relatively warm, moist surface air (“mini cold front”)
Shelf/Roll Cloud
May often form on leading edge of gust front
Supercell
Thunderstorm consisting of a single very powerful cell that can extend to heights of 65000 ft and have a diameter of 12-30 miles
Mesocyclone
Vertical cylinder of cyclonically rotating air that develops in updraft of a supercell, often precedes damaging hail and tornadoes
- Caused by increase in wind speed and change in direction with height
Squall Line
Narrow band of thunderstorms
- Usually develops 60 - 80 miles in advance of cold front
Where can a Squall Line form
Along a dryline
Mesoscale Convective Complex (MCC)
Many individual thunderstorms organized into a large oval to circular cluster
Where does MCC most frequently occur
In the Great Plains
Lightning
A sudden flash of light generated by the flow electrons between areas of opposite charge
