Severe Storms Flashcards
what are the 3 conditions needed for a storm?
- abundance of moisture
- mechanism of lift
- unstable air (rise only if there is warmer air around it)
what are 2 things that affect the growth of storms (growth limits of storms)
the rising air meets stable air above it
the rate of condensation
condensation ___ with height
decreases
involving the rate of condensation… there is not enough latent heat to keep cloud __ that surrounding air
warmer
Single cell thunderstorms last about ___ minutes
and are about ___ km in diameter
30 minutes
24 km in diameter
what is the thunderstorm capital of the world?
The U.S.
How are thunderstorms classified?
they are classified by the mechanism that causes the air to rise
What are the 2 different kinds of thunderstorms?
air mass
frontal
Air mass thunderstorms:
mechanism of lift=
reaches max at ____
uneven heating
mid-afternoon
there are 2 types of air mass thunderstorms, what are they? and why are they created?
mountain: orographic lifting
sea-breeze: extreme temperature
in a frontal thunderstorm, what is the mechanism of lift?
advancing cold front
in a frontal thunderstorm, the initial lift occurs___
off a steep leading edge of a front
thunderstorms that occur at night have to be ___ thunderstorms
frontal
what are the 3 stages of development in thunderstorms?
- Cumulus
- mature
- dissipation
in the cumulus stage, there is nearly a ___ ___ of air, the updraft ___ ___ into the upper clouds. Then it ___ and ___ ___. Precipitation begins
vertical rise
moves moisture
condenses
releases heat
what happens when precipitation falls in the mature stage of a storm?
the precipitation cools the air around it as it falls
In the mature stage of a storm, cooled air becomes denser and then ___ ___ and this causes ___.
sinks rapidly
downdrafts
In the mature stage, updrafts and downdrafts cause what?
convection cells
In dissipation, ___ cool the earth
downdrafts
In dissipation, the earth is cooled by ___, updrafts slow, then ___. This causes precipitation to ___.
downdrafts
stop
no longer form
what is the most common type of storm?
Mulit-cell storm
what are multi-cell storms?
clusters of single cell storms
what cell storms are self sustaining?
super cells
in super-cells, you are able to see movement inside the cloud which is…?
intense rotating of 240 km/h
about how long do the duration of super-cell storms last?
1 hour
super-cells are ___% of all storms
10%
what can super-cell storms rise/trigger?
tornadoes
what is the mechanism of lift involving super-cells?
a cold front with upper level low pressure
when there is upper level low pressure, what is created?
high winds underneath the low pressure
convection cells are able to continuously ___
regenerate
super-cells are able to _____
lift a continuous supply of warm humid air
what season does hail mostly occur? and how is it formed?
spring
formed when super cooled water freezes in ice pellet
how does hail grow in size?
it rides the “convection belt”
it rides updrafts and downdrafts
when hail is the largest, what does this mean for the updrafts?
more powerful the updrafts= larger hail
on the convection belt longer
where are squall lines found?
found in warm areas of wave cyclone about 160 km ahead of cold front
what do squall lines produce?
strong straight line winds, hail, sometimes tornadoes
what was the main cause of damage in the SL storm of 1998? and what was it called?
straight line winds
Derecho event
what was the twisting damage in the 1998 storm caused by?
gustanadoes
what are down-burst winds?
concentrated straight line winds (wind does not disperse when it hits surface)
when wind speed and direction change suddenly in the event of a tornado, what is this called?
wind shear
what kind of cell thunderstorm form tornadoes?
super-cell
On a radar, what indicates where a tornado can form?
hook echos
what are the 3 things that the Enhanced Fujita scale depend on?
time on ground
path of destruction
wind speed
