Transcript Tornado PowerPoint - Junction Hill C

Tornadoes
• A tornado is a
violently rotating
column of air in
contact with the
ground and out from
a cumulonimbus
cloud.
• Tornadoes are
capable of inflicting
extreme damage.
• Tornadoes can be categorized as "weak",
"strong", and "violent"; with weak
tornadoes often having a thin, rope-like
appearance.
• About 7 in 10 tornadoes are weak, with
rotating wind speeds no greater than
about 110 MPH.
• The typical strong tornado often has a
"classic" funnel-shaped cloud associated
with the whirling updraft. Rotating wind
speeds vary from 110 to 200 MPH.
• Nearly 3 in 10
tornadoes are
strong, such as
this twister on
the plains of
North Dakota
• Less than 2 percent of all
tornadoes reach the 200+
MPH violent category.
• Most violent tornadoes only
produce home-leveling
damage within a very small
area
• Less than 5 percent of the
5,000 affected homes in
Wichita Falls, Texas were
leveled by this massive 1979
tornado.
A Tornado Develops
Fujita Tornado Intensity Scale
The Fujita scale, or F scale,
categorizes tornado severity based
on observed damage to man-made
structures and not on recorded wind
speeds.
F0: Gale tornado (40-72 mph); light damage.
Some damage to chimneys; break branches
off trees; push over shallow-rooted trees;
damage to sign boards.
F1: Moderate tornado (73-112 mph); moderate
damage. The lower limit is the beginning of
hurricane wind speed; peel surface off roofs;
mobile homes pushed off foundations or
overturned; moving autos pushed off the roads.
F2: Significant tornado (113-157 mph);
considerable damage. roofs torn off frame houses;
mobile homes demolished; boxcars pushed over;
large trees snapped or uprooted; light-object
missiles generated.
• F3: Severe tornado (158-206 mph); Severe damage.
Roofs and some walls torn off well-constructed
houses; trains overturned; most trees in forest
uprooted; heavy cars lifted off ground and thrown.
• F4: Devastating tornado (207-260 mph); Devastating
damage. Well- constructed houses leveled; structure
with weak foundation blown off some distance; cars
thrown and large missiles generated.
• F5: Incredible tornado (261-318 mph); Incredible
damage. Strong frame houses lifted off foundations
and carried considerable distance to disintegrate;
automobile sized missiles fly through the air in excess
of 100 yards; trees debarked; incredible phenomena
will occur.
Some Significant Tornadoes
• Oklahoma City, OK, May 3, 1999: On Monday
evening, May 3, a long track F5, violent tornado
traveled from near Chickasha, Oklahoma, to just
east of Oklahoma City, Oklahoma. Along its path
this tornado produced areas of F5 damage to
both rural sections of central Oklahoma as well
as densely populated areas of Oklahoma City
and its suburbs. In the wake of this single
tornado, there were 42 people left dead, several
hundred injured and over 1 billion dollars in
damage.
• The Tri-State Tornado Outbreak of March 18, 1925
killed 689 people in Missouri, Illinois and Indiana.
Murphrysboro, Ill., had 234 of those deaths, and
West Frankfort, Ill., had 127.
• Other deadly tornadoes include the May 6, 1840
tornado which killed 317 people in Natchez,
Mississippi; the May 27, 1896, tornado which killed
255 in St. Louis, Missouri. Tornadoes on successive
days in 1936 killed 216 people in Tupelo,
Mississippi, on April 5; and 203 people in
Gainesville, Georgia, on April 6.
Biggest, Costliest Outbreaks
• The April 3-4, 1974 Super Outbreak was the
largest known outbreak, with 148 tornadoes in 11
states, killing 315 people, injuring more than
5,300 and causing $600 million in damages.
Alabama, Kentucky and Ohio were the states
hardest hit. Perhaps the most notable tornado of
the outbreak was one which touched down
southwest of Xenia, Ohio. The violent tornado
destroyed half the town, killing 34 and causing
property damages of more than $100 million.
The End …..
Or is it???