Thunderstorms and Tornadoes

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Thunderstorms and Tornadoes
By Karen Williams, Danielle Clark, and Alexa
Caturay
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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.

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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.

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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.

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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.
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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.
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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.
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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.

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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.

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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.

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What causes these storms?
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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.

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TORNADO ALLEY USA
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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.

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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

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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.
  

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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.    

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How dangerous are tornadoes?

• Fujita Tornado Scale

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

• Fujita Tornado Scale

F-1 73-112 mph. Mobile homes are pushed off of
their foundation or overturned.
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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.
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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.
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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.
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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.
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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

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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.

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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.

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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.

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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.

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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.

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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.

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Trivia!

• Where are tornadoes most common?
• Although tornadoes form all over the world, they
  are more frequent and stronger in US.

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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.

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Trivia!

• What is a tornado that forms over a desert
  called?
• A tornado that forms over a desert is called a
  dust devil.

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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.

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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.

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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.

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Trivia!

• How do we know how severe a tornado is?
• Scientists cant rate or know how strong a
  tornado is until after it is over

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THANK YOU!

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Credits

• Information and Pictures
• http//www.fema.gov/hazards/tornadoes/tornadof.sht
  m
• http//www.cnn.com/2005/WEATHER/04/06/tornadoesmis
  sissippi
• 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