Transcript What are the stages of development in a Thunderstorm?

Thunderstorms
&
Tornadoes
What are the stages of development in a Thunderstorm?
Three stages have been
identified in ordinary
thunderstorms:
a)
Cumulus stage: an
unstable atmosphere and
vertical updrafts
b)
Mature stage
c)
Dissapating
stage:weakening updrafts
and loss of the fuel
source.
Mature Stage Thunderstorm
Video: Hail.asf
Dissipating Stage of Thunderstorm
Diagram of a developing Thunderstorm
Trailing Stratified Clouds
Pre-Frontal Squall Line Storms on Radar
What causes lightning during a thunderstorm?
Charged layers in the cloud are
formed by the collision of
hailstones and ice with the
cumulonimbus cloud.
When the negative charge near
the bottom of the cloud is large
enough to overcome the air's
resistance a lightning bolt
forms.
Video: Lightning_Strikes.asf
What causes thunder to form?
The rapid heating of air by a
lightning bolt creates an explosive
shock wave called thunder, which
requires approximately 3 seconds to
travel about 1 mile.
What is a tornado?
Video:
All_About_Tornadoes_and_Tornado_Alley.asf
A rotating column of air
ranging in width from a few
yards to more than a mile and
whirling at destructively high
speeds, usually accompanied
by a funnel-shaped downward
extension of a cumulonimbus
cloud.
When do tornadoes occur?
Nearly 75% of tornadoes form from March to July, and are more likely when warm
humid air is overlain by cooler dryer air to cause strong vertical lift.
What scale measures tornado intensity?
Once the storm is observed, or has passed, the Fujita scale of F0 – F5 is used to
classify tornadoes according to their rotational speed based on damage done by the
storm.
How does a tornado begin to spin (vorticity)?
Spinning horizontal vortex tubes created by surface wind may be tilted
and forced in a vertical path by updrafts. This rising, spinning, and
often stretching rotating air may then turn into a tornado.
What is a “supercell”?
A thunderstorm with a persistent rotating updraft. While rare, it
produces the most severe weather such as tornadoes, strong
winds, and hail.
Overhead view of a
Super Cell
Rotating Clouds
What is a waterspout?
Warm, shallow coastal water is
often home to waterspouts,
which are much smaller than an
average tornado, but similar in
shape and appearance.
The waterspout does not draw
water into its core, but is a
condensed cloud of vapor.
A waterspout may, however, lift
swirling spray from the water as
it touches the water surface.