Transcript tornado - Natural Disasters

What does a redneck divorce and
a tornado have in common ?
Either way, someone’s bound to
lose a trailer.
By Josh Smith
Corey Withers
What Are Tornadoes ?
• Tornadoes are columns of
violently rotating air
developed in a convectional
cloud and are in contact with
the ground.
• Tornadoes usually occur
along with thunderstorms in
the spring and summer in the
mid-latitudes of the
hemispheres.
• Tornadoes are known for
generating the strongest
winds on the planet.
How Are Tornadoes Formed ?
• Prior to a developing
thunderstorm, a change in wind
direction and an increase of wind
speed with increasing height,
forms a horizontal spinning
motion.
• Rising air from the thunderstorm
updraft tilts the spinning column
of air so it is now vertical.
• This “funnel” of air extends down
from the cloud towards the
ground. When it reaches the
ground, a tornado is created.
Conditions Necessary For
Tornadoes To Form
• Very warm, humid air
• Very cool, dry air to the west
and south
• Front from the west moves and
replaces warm moist air
• High in the sky, the warm moist
air rises very far, fast
• Upper level wind stream moves
air away from rising column
• Warm, wet air driven east by
strong cold front
How Do Tornadoes End ?
Tornadoes begin to diminish
when any of the factors that
caused the tornado begin to
deteriorate.
Where Do They Occur ?
Tornadoes occur
along the midlatitudes of the
hemispheres. In
Canada we don’t
suffer much at all
from them, but to
the left is a
tornado activity
map of the United
States.
How Are Tornadoes Measured ?
• Tornadoes intensity’s are
measured with the Fujita
Scale.
• The Fujita Scale was
created by a man named
Tetsuya “Ted” Fujita,
• (1920-1998)
• This is a picture of Dr.
Fujita with his Tornado
simulator.
The Fujita Scale
The Fujita Scale goes from F0 through to F6. F0 being a weak
tornado and F6 being a very violent tornado. Here is a chart
showing the phrase for each type of tornado, and the wind speed.
F0
Gale Tornado
40-72 mph
F1
Moderate Tornado
73-112 mph
F2
Significant Tornado
113-157 mph
F3
Severe Tornado
158-206 mph
F4
Devastating Tornado
207-260 mph
F5
Incredible Tornado
261-318 mph
F6
Inconceivable Tornado
319-379 mph
Th Fujita Scale 2
Above is a pie graph
showing the percentage of
all tornadoes that are each
intensity class.
Above is a pie graph showing the
percentage of death’s caused by
different strengths of tornadoes.
The Fujita Scale 3
F0- Damage that could be caused by
these tornadoes is chimney damage,
broken branches, and shallow rooted
trees are toppled.
F1-Roof surfaces peeled off, broken
windows, snapped tree trunks, trailers
could be toppled, attached garage
damages.
F2- Roof structures damaged,
manufactured homes are destroyed,
debris becomes airborne, larger trees
snap or become uprooted.
The Fujita Scale 4
F3- Roofs and walls can be torn from
structures, small buildings destroyed, many
trees throughout forest could be uprooted.
F4-Well constructed houses are destroyed,
structures could be lifted from foundations
and carried a distance, cars get blown some
distance, larger debris becomes airborne.
F5-Strong frame houses are lifted from
foundations, reinforced concrete structures
are damaged, vehicles become airborne,
large trees completely debarked.
Do They All Look Alike ?
No, there are many different shapes and sizes of tornadoes. Above is
an example of a “wedge” tornado.
Shelters
In the United States, Tornado Alley to be exact, many homes often
have shelters. Shelters are usually small storm cellar-like structures
that are usually in ground, but some can be above ground.
Some History
The year 1896 was a record year for killer tornadoes in the united
states, having over 40 killer tornadoes including the only tornado
ever to kill more than 100 people in two separate cities.
On May 27, 1986 two tornadoes touched down at the same time,
but from two different thunderstorms. One of them leveled many
farms, and the other was the third deadliest in US history.
It cut a half a mile path through St.Louis, Missouri.
Interesting Facts
Very intense tornadoes
often have more than one
vortex, or funnel moving
around the center vortex.
Deadliest Tornado in US History
The deadliest tornado in United States history occured at
about 1:01 PM on March 18, 1925.
This tornado set records for speed, path length and death
rate.
Tornado Safety
Prior to Storm:
During a Storm:
If your not home:
Homes that have
had any scare of a
tornado should have
a practiced plan for
a tornado.
Avoid windows and
easily breakable
objects, stay out of
automobiles, move to
planned shelter. If you
don’t have a storm
shelter, move to lowest
area possible, under a
strong structure.
Avoid being in
automobiles and/ or in
mobile homes as they
can be thrown around.
There should also
be random radio or
t.v. checks, just in
case.
Also, overpasses are
dangerous in
tornadoes because
wind speeds increase
when going under
overpass.
Tornado Safety 2
The government does offer aid when it comes to Tornado safety.
There is an agency called FEMA or Federal Emergency
Management Agency. FEMA provides people in high-risk
tornado/hurricane area’s with a lot of information about residential
and community shelters.
They help people repair their broken homes and buildings, provide
victims shelter, and also they teach people how to be prepared and
what to do in the event of a tornado.
Why They Occur in Central US
There is a high rate of tornado occurance in
Central United States due to the continental
polar air mass from the north merging with
the Tropical air from the south.
Two Tornadoes
Funnels That Didn’t Reach The
Ground
Devastating Funnels
Possible Damage
Bibliography
http://www.chaseday.com/tornadoes.htm
http://whyfiles.org/013tornado/index.html
http://www.usatoday.com/weather/tg/wtorwhat/wtorwhat.htm
http://www.tornadoproject.com/safety/shelters.htm
http://rsd.gsfc.nasa.gov/goes/text/hotstuff.html
http://www.stormvideo.com/tornado.html
http://www.mysteries-megasite.com/mysterymovies/tornmovie.html
http://www.fema.gov/mit/saferoom/
http://www.disastercenter.com/tornado.htm
http://teacher.scholastic.com/researchtools/articlearchives/weather/tornado.htm
http://www.tornadoproject.com/fscale/fscale.htm
http://web.msu.edu/~fujita/tornado/ttfujita/index.html
http://www.usgs.gov/themes/animationmap.html
Possible Damage
The following is a video showing the possible effects
of a strong tornado in a rural area.
It shows very well how a tornado can also be called a
“vortex” because of the damage done by the
“sucking” into the center.