Tornado_Presentation by xiaopangnv


How does a tornado form?
•A tornado begins in a severe thunderstorm
called a supercell (which lasts longer than a
regular thunderstorm.)

•First, the wind coming into the storm starts to
swirl forming a funnel.

•Next, the air in the funnel spins faster and
faster creating a very low pressure area that
sucks more air (and possibly objects) into it.
  Super Cell
   of a

            NOAA – Public Domain
How long does a tornado last?
Tornadoes can last any where from a few seconds
up to an hour.

How do tornadoes rotate?
In the Northern Hemisphere most spin
counterclockwise (cyclonically), but a few spin
When does a tornado form?
•The severe thunderstorms which produce
tornadoes form when cold, dry, polar air meets
warm, moist, tropical air.
•Also, the atmosphere needs to be very
                          FEMA – Public Domain

This weather pattern is most common in the
central section of the United States also known as
Tornado Alley.
Tornadoes throughout the World

           NOAA – Public Domain
       What time of year do
        tornadoes form?
• Tornadoes can form any time during the year,
  however, they mostly form in May.

• More severe tornadoes form earlier in the season.
   – The most damage is caused in April.

• The more North you go, the later the peak tornado
  season. This is because it takes longer to warm the
  northern parts of the plains thus causing a delay in
  the season’s start.
   – For example, Pennsylvania and Northern NY have their peak seasons
     in the summer.
    Steps to the
Formation of a Tornado

Wind sheer    The updraft
                                The updraft
starts wind   starts the air
                               starts rotating
 spinning       spinning
         Tornado Watch
• NOAA issues this when conditions are
conducive for the formation of severe
thunderstorms and tornadoes.

        Tornado Warning
• A tornado has been actually observed or its
occurrence is imminent
• A funnel cloud has been observed or radar
has shown rotation of winds in a thunderstorm

Copy HW into your agenda: organize your notebook

Do Now: #93-Copy the question and answer it
Describe in detail how a tornado forms. (3 steps)
       Safety Procedures
          In a house with a basement
• Avoid windows.

• Get in the basement and under some kind of
  sturdy protection (heavy table or work bench), or
  cover yourself with a mattress or sleeping bag.

• Know where very heavy objects rest on the floor
  above (pianos, refrigerators, waterbeds, etc.)
  and do not go under them. They may fall down
  through the floor above you.
        Safety Procedures
  In a house with no basement, dormitory, or
              apartment building
• Go to the lowest floor, small center room (like a
  bathroom or closet), under a stairwell, or in an
  interior hallway with no windows.

• Crouch as low as possible to the floor, facing
  down; and cover your head with your hands.

• Even in an interior room, cover yourself with
  some sort of thick padding to protect against
  falling debris in case the roof and ceiling
        Safety Procedures
                     In school
• Go to the interior hall or room in an orderly way
  as you are told.

• Crouch low, head down, and protect the back of
  your head with your arms.

• Stay away from windows and large open rooms
  like gyms and auditoriums.
How are tornadoes classified?
• Tornadoes used to be classified using the
  Fujita Scale.

• Dr. Fujita designed his
  scale equating different
  levels of damage due
  to wind speed.

• Categories were from
  F-0 through F-5

• F-5 were the strongest.
F-5 tornado
F-4 Damage
F-4 Tornado
F-3 Tornado
         How are tornadoes

• As of February 1, 2007 a new scale called
  the Enhanced Fujito Scale – EF was
  accepted for use in classifying tornadoes.

• It rates tornadoes from EF-0 through EF-5.
      Enhanced Fujita Scale
                                   DERIVED EF        OPERATIONAL EF
                                     SCALE               SCALE

           Fastest    3 Second            3 Second            3 Second
  F                                EF                  EF
           1/4-mile      Gust                Gust                Gust
Number                           Number              Number
            (mph)       (mph)               (mph)               (mph)

  0         40-72       45-78      0       65-85       0       65-85
  1         73-112      79-117     1       86-109      1       86-110
  2        113-157    118-161      2      110-137      2      111-135
  3        158-207    162-209      3      138-167      3      136-165
  4        208-260    210-261      4      168-199      4      166-200

  5        261-318    262-317      5      200-234      5      Over 200
          May 2007 Tornadoes
• The Storm Prediction Center had issued a moderate risk
  across portions of Kansas, Oklahoma and Nebraska on May
  4, while temperatures were in the mid to high 80s°F.

• A powerful low pressure system developed across the
  southern Rockies and a warm front provided additional
  moisture coming from the Gulf of Mexico increasing the
  instability in the atmosphere across much of the region.

• In addition a dry line, which marks a divided line between the
  dry and humid air mass, was positioned near the areas
  affected by the outbreak also increasing instability.

• All the ingredients were present for the developing of super
  cell thunderstorms that can lead to damaging wind, large hail
  and tornadoes.
  May 2007 – Greensburg, KS
• The National Weather Service rated the Greensburg,
  Kansas tornado as an EF-5 on the Enhance Fujita Scale –
  the highest category.
• A storm of this magnitude is the first in 8 years in the US.
  The last was May 3rd, 1999 in Oklahoma.

• The tornado carved a track 1.7 miles wide and 22 miles
  long. going non-stop for 30 minutes.

• Maximum winds were estimated at 205 mph.

• From Friday to Sunday, the National Weather Service
  received 32 reports about 25 SEPARATE tornadoes in
  southwest and south central Kansas alone.
Radar of Super cell that resulted in Greensburg Tornado
Before and after satellite images of Greensburg, KS

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