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					Thunderstorms
and Tornadoes


           By: Karen Williams,
               Danielle Clark,
            and Alexa Caturay
Thunderstorms
and Tornadoes
   Thunderstorms and tornadoes are
     among the most destructive
     weather systems.
   In this presentation we will discuss
     the causes and effects of these
     weather systems and what one
     can do to be prepared for them.
What are
Thunderstorms?
       Thunderstorms are storms with
         thunder, lightning, and usually
         heavy rain or hail.
       While not as dangerous as other
         extreme weather conditions,
         thunderstorms can still inflict much
         damage.
What causes these
storms?
For a thunderstorm to occur, the following
  ingredients must be present:

   Moisture which forms clouds and rain.

   Warm air, which is unstable and rises rapidly.

   Lifts, which are breezes capable of lifting the air
    to form thunderstorms.
How do thunderstorms
develop?
Thunderstorms develop in warm, moist air in
advance of eastward-moving cold fronts. These
thunderstorms often produce large hail, strong
winds, and tornadoes.
Before thunderstorms develop, a change in wind
direction and an increase in wind speed create an
invisible spinning effect in the lower atmosphere.
How do thunderstorms
develop?
Rising warm air carries moisture up into
cooler air where the moisture condenses and
builds cumulus clouds vertically, thus creating
a thunderhead.
After a large cloud has built rain, hail, or other
forms of precipitation usually begin to fall.
This lasts anywhere from ten minutes to
several hours depending on the severity of
the storm.
The storm will eventually dissipate with rain
falling less intensely.
When and where are
thunderstorms most likely
to occur?

   Thunderstorms can occur at any time of the
   year, most of them occur on the afternoon
   during hot summer days. They are fairly
   common and occur all over the world.
Why are thunderstorms
dangerous?
During a thunderstorm, even as it tapers down,
  lightning and flash floods can pose threats.
The other big threat posed by thunderstorms is
  the creation of tornadoes.
What are Tornadoes?
     Tornadoes are the most violent of
       extreme weather conditions
       suffered on earth. They consist of
       rotating columns of air ranging in
       width from a few yards to more
       than two killometers, moving at
       destructively high speeds, usually
       accompanied by a funnel-shaped
       downward cloud.
What causes these
storms?
Tornadoes are caused by violent thunderstorms.
An abrupt change in wind speed and direction as
  well as extreme instability in the weather patterns
  helps the formation of tornadoes. These
  conditions are usually found before a cold front.
The updrafts and downdrafts present in a
  thunderstorm create the spinning effect that
  makes tornadoes so dangerous.
What causes these
storms?
Where and when are
tornadoes most likely to
occur?
  Tornadoes can occur all over the world, however
    they are most likely to occur in the United States,
    east of the Rocky Mountains. An average 800
    tornadoes are reported a year in this area and due
    to the frequency of them, it has been dubbed
    ‘Tornado Alley’. In Canada, most tornadoes occur
    in southern Ontario and Alberta, and in
    southeastern Quebec.
  Prime tornado conditions are in the spring, in
    particular in late May. Most tornadoes happen in
    the mid or late afternoon. Tornadoes do not often
    occur in January or February.
TORNADO ALLEY: USA
Are tornadoes likely to
happen here?
      There have been few occurrences of
        tornadoes in the Windsor area.
      The last tornado to hit Windsor
        occurred in 1974. It left 30 dead
        and many injured and caused a
        total of $500 000 worth of damage.
Are tornadoes likely to
happen here?
      Prior to this, a tornado occurred in
        1946. It left 17 dead and many
        injured. It also caused a
        conservatively estimated $1.5
        million in damage
Where else have tornadoes
occurred?
      The most recent tornado occurred on
        April 7th, 2005 in Mississippi. It
        was severe enough to cause
        extensive damage to homes,
        uproot trees, and topple telephone
        poles. A total of 19 tornadoes
        were reported between 6 a.m. and
        2 p.m.
How dangerous are
tornadoes?
Tornadoes are the most violent of storms. The potential of
  destruction caused by tornadoes depends on the Fujita
  tornado intensity scale. The weakest on the scale, a
  zero (0), can cause branches and windows to break
  and shallow rooted trees to be pushed over with winds
  reaching up to 118 km per hour. The most violent type
  of tornado is 5 on the f-scale. This type of tornado
  causes cars to be thrown as far as 100 meters, houses
  to be lifted off of their foundations and trees to be
  uprooted with winds reaching up to 513 km per hour.
How dangerous are
tornadoes?
Fujita Tornado Scale




F-0: 40-72 mph. Chimney damage occurs and tree
branches are broken
How dangerous are
tornadoes?
 Fujita Tornado Scale




F-1: 73-112 mph. Mobile homes are pushed off of their
foundation or overturned.
How dangerous are
tornadoes?
Fujita Tornado Scale




F-2: 113-157 mph. Considerable damage occurs,
including the demolition of mobile homes and
uprooting of trees.
How dangerous are
tornadoes?
 Fujita Tornado Scale




F-3: 158-205 mph. The walls and roofs of buildings are
destroyed, trains overturned, and cars picked up and
thrown.
How dangerous are
tornadoes?
 Fujita Tornado Scale




F-4: 206-260 mph. Extnsive damage is done with the
well constructed walls and roofs of buildings
completely leveled.
How dangerous are
tornadoes?
Fujita Tornado Scale




F-5: 260-318 mph. Extreme damage is done. Homes
can be lifted from their foundations and carried
considerable distances, and automobiles thrown more
than 100m.
Tornado Safety.
When a tornado is coming, you have only a short amount of time to
   make life-or-death decisions. Advance planning and quick
   response are the keys to surviving a tornado.
 BEFORE
Conduct tornado drills.
   Designate an area as a shelter, and practice having everyone go
   there in response to a tornado threat.
Make an emergency supply kit that includes:
Flashlight and extra batteries
  Portable, battery-operated radio and extra batteries
  First aid kit and manual
  Emergency food and water
  Non-electric can opener
  Essential medicines
  Cash and credit cards
  Sturdy shoes
Tornado Safety.
Learn these tornado danger signs:

   An approaching cloud of debris can mark the location
    of a tornado even if a funnel is not visible.
   Before a tornado hits, the wind may die down and the
    air may become very still.
   Tornadoes generally occur near the trailing edge of a
    thunderstorm. It is not uncommon to see clear, sunlit
    skies behind a tornado.
Tornado Safety.
DURING
If at home:

   Go at once to a windowless, interior room; storm cellar;
    basement; or lowest level of the building.
   If there is no basement, go to an inner hallway or a smaller
    inner room without windows, such as a bathroom or closet.
   Get away from the windows.
   Go to the center of the room. Stay away from corners
    because they tend to attract debris.
   Get under a piece of sturdy furniture such as a workbench or
    heavy table or desk and hold on to it.
   Use arms to protect head and neck.
   If in a mobile home, get out and find shelter elsewhere.
Tornado Safety.
DURING
If at work or school:

   Go to the basement or to an inside hallway at the lowest level.
   Avoid places with wide-span roofs such as auditoriums,
    cafeterias, large hallways, or shopping malls.
   Get under a piece of sturdy furniture such as a workbench or
    heavy table or desk and hold on to it.
   Use arms to protect head and neck.
If outdoors:

   If possible, get inside a building.
   If shelter is not available or there is no time to get indoors, lie
    in a ditch or low-lying area or crouch near a strong building.
    Be aware of the potential for flooding.
   Use arms to protect head and neck.
Tornado Safety.
DURING
If in a car:

   Never try to outdrive a tornado in a car or truck.
    Tornadoes can change direction quickly and can
    lift up a car or truck and toss it through the air.
   Get out of the car immediately and take shelter in a
    nearby building.
   If there is no time to get indoors, get out of the car
    and lie in a ditch or low-lying area away from the
    vehicle. Be aware of the potential for flooding.
Tornado Safety.
AFTER

   Help injured or trapped persons.
   Give first aid where needed.
   Don't try to move the seriously injured unless they are in
    immediate danger of further injury.
   Call for help.
   Turn on radio or television to get the latest emergency
    information.
   Stay out of damaged buildings. Return home only when
    authorities say it is safe.
   Use the telephone only for emergency calls.
   Clean up dangerous spills immediately. Leave the building if
    you smell gas or chemical fumes.
   Take pictures of the damage both to the house and its
    contents for insurance purposes.
What happens Next?

 Eventually all storms dissipate. They either
   move on to another region, or lose all of
   their energy and disperse. Rain slows then
   stops, clouds disappear, and winds cease.
Trivia!
Where are tornadoes most common?

Although tornadoes form all over the world,
  they are more frequent and stronger in US.
Trivia!
What is a tornado that forms over water
 called?

A tornado that forms over warm water is
  called a waterspout. The water in the spout
  comes from condensation, not from the
  water below.
Trivia!
What is a tornado that forms over a desert
 called?

A tornado that forms over a desert is called a
  dust devil.
Trivia!
How fast do most tornadoes spin?

The average forward speed of a tornado is 30
  to 40 mph but can go as fast as 70mph and
  has rotational speed that can be more than
  300mph.
Trivia!
What was the worst tornado recorded?

The worst series of tornadoes in history was
  on March 18, 1925. About 689 people were
  killed in Missouri, Illinois and Indiana.
Trivia!
In which direction do most tornadoes spin?

Usually in the northern atmosphere tornadoes
 turn counter-clockwise. In the southern
 hemisphere, tornadoes usually turn
 clockwise.
Trivia!
How do we know how severe a tornado is?

Scientists can’t rate or know how strong a
  tornado is until after it is over
THANK YOU!
Credits
 Information and Pictures:

 http://www.fema.gov/hazards/tornadoes/tornadof.shtm
 http://www.cnn.com/2005/WEATHER/04/06/tornadoesmississippi
 http://www.exn.ca/Stories/1999/05/04/54.asp
 www.noaa.gov/tornadoes.html
 http://www.gettyimages.com

 Songs and Sounds:

 Microsoft PowerPoint Sound Clip Gallery
 ‘Rainy Days and Mondays’ – The Carpenters
 ‘Raindrops Keep Falling’ – BJ Thomas
 ‘I Can See Clearly Now’ – Johnny Nash

				
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posted:2/7/2013
language:English
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