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STRIKE FINDER
Thunderstorm Types
There are several types of thunderstorms: The air mass thunderstorm, the
severe thunderstorm, and squall-line thunderstorm. An air mass
thunderstorm consists of one
the severe thunderstorm is composed of
for up to two hours.
Air Mass Thunderstorm
The Air Mass Thunderstorm grows quickly and is contained within a single
cell. At maturation, the thunderstorm is normally self-destructive. Updrafts
elevate water. Water accumulates in the upper areas of the storm. When
the upward source can no longer support the accumulated water mass, it
rains. The rainfall (downward) overwhelms and strangles the lifting process
(upward), and the storm dissipates.
Severe Thunderstorm
The Severe Thunderstorm develops when a number of single
and produce more cells (multicells), thus sustaining the life of the storm.
Specifically, the strong updraft tilts and twists moisture into the upper air
support. With strong upper atmosphere winds (for example, the Jet
Stream,) the storm tilts or leans downwind. This is evident by the highest
portion of the cloud spreading outward (downwind), and forming an anvil
shape, (see Figure 36, p.43).The water carried upward will accumulate and
rain downwind, possibly far ahead of the storm's updraft core. Consequently
the mature stage does not initiate the dissipating stage by strangling the
updraft element.
A severe thunderstorm has a greater intensity than an air mass
thunderstorm. This is evident by the weather it produces: winds of 50
knots or greater, three-quarters of an inch or larger destructive hail, and/or
strong tornadoes.
Squall-Line Thunderstorm
Squall line storms are the most disruptive to aviation because they form in
lines that can stretch a few hundred miles, and individual storms in the lines
can be fierce. Strictly speaking, the lines of storms usually referred to as
squall-lines are "pre-frontal squall-lines." Squall lines often trail large areas
of stratus clouds with low ceiling and visibility that can linger for hours.
42
DIGITAL WEATHER AVOIDANCE
cell
and lasts less than one hour, whereas
multicells
or supercells, and lasts
cells
interact
PILOT'S
GUIDE
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