Transcript Tornado Notes

February 26, 2016
Objective: I will explain how, where, and why tornadoes
form.
Entry Task:
• What is the difference between climate and weather?
• What is the difference between a tornado and a
hurricane?
Agenda: Intro to Storms - Tornadoes
1) Tornado notes
Homework: No Homework
Tornadoes
What is a tornado?
What is a Tornado?
• A violently rotating column of
air
• Extends from a thunderstorm
to the ground.
What is a thunderstorm?
• A local storm
• Produced by a cumulonimbus
cloud
• Always accompanied by lightning
and thunder
• Usually with strong gusts of wind,
heavy rain, and sometimes with
hail.
Tornadoes are found most
frequently in the US
Average year in USA:
• 1,200 tornadoes
• 70 fatalities
• 1,500 injuries
Tornado Alley:
• States at the highest
risk of getting a tornado
Includes:
Arkansas, Iowa, Kansas,
Louisiana, Minnesota,
Nebraska, North Dakota,
Ohio, Oklahoma, South
Dakota, and Texas.
How does a tornado form?
Most tornadoes form from
thunderstorms
Ingredients:
• Warm, moist air
• Cool, dry air
When these two air masses meet,
they create instability in the
atmosphere.
North America has no major eastwest mountain range to block air
flow between these two areas. This
allows for many collisions of warm
and cold air; creating the conditions
necessary for tornadoes to form.
Tornado
Alley
How does a tornado form?
Step 1: Wind Shear
• Wind shear (a change in wind
direction)
• Creates an invisible,
horizontal spinning effect in
the lower atmosphere.
Step 1: Spinning in the
lower atmosphere
How does a tornado form?
Step 2: Up Drafting
• Rising air within the
updraft tilts the rotating air
from horizontal to
vertical.
Step 2: Lifted and tilted from
horizontal to vertical
How does a tornado form?
Step 3: Formation &
Extension
• An area of rotation, 2-6
miles wide, now extends
through much of the
storm.
Step 3: Extending and Forming
Tornadoes Take Many Shapes and Sizes
Strong Tornadoes
F2-F3
Weak Tornadoes
F0-F1
•
•
•
•
88% of all tornadoes
Less than 5% of tornado
deaths
Lifetime 1 - 10+ minutes
Winds less than 110 mph
•
•
•
•
11% of all tornadoes
Nearly 30% of all tornado
deaths
May last 20 minutes or longer
Winds 110-205 mph
Violent Tornadoes
F4-F5
•
•
•
•
Less than 1% of all
tornadoes
70% of all tornado deaths
Lifetime: Hour +
Winds: 205 mph +
Fujita Scale of Tornado Intensity
SCALE WIND SPEED
POSSIBLE DAMAGE
F0
40-72 mph
Light damage: Branches broken off trees; minor roof damage
F1
73-112 mph
Moderate damage: Trees snapped; mobile home pushed off
foundations; roofs damaged
F2
113-157 mph
Considerable damage: Mobile homes demolished; trees
uprooted; strong built homes unroofed
F3
158-206 mph
Severe damage: Trains overturned; cars lifted off the
ground; strong built homes have outside walls blown away
F4
207-260 mph
Devastating damage: Houses leveled leaving piles of
debris; cars thrown 300 yards or more in the air
F5
261-318 mph
Incredible damage: Strongly built homes completely
blown away; automobile-sized missiles generated
Where and when tornadoes occur?
• Any time of the year
• Any time of the day
• Most likely to occur between 3
and 9 p.m.
• Have occurred in every state
• Most common east of the
Rocky Mountains during the
spring and summer months.
Deport, Texas
Hoxie, Kansas
Northeast, Nebraska
Waterspouts
• Weak tornado that
forms over water.
• Common along the
Gulf Coast.
• Waterspouts can
sometimes move
inland, becoming
tornadoes causing
damage and injuries.
Washington Tornados
Puget Sound
Washington Tornados
Monroe – June 2010
Washington Tornados
Kent – December 1969 – F3
Nov. 9, 2005 1:45-2:40pm
Teacher of The Day For Hawthorne
Elementary ELP 2nd Grade: Ms. Dawn
Tornado Facts
• Tornadoes may appear nearly transparent until dust and
debris are picked up or a cloud forms within the funnel.
• The average tornado moves from southwest to northeast, but
tornadoes have been known to move in any direction.
• The average forward speed is 30 mph but may vary from
nearly stationary to 70 mph.
• The strongest tornadoes have rotating winds of more than
250 mph.
• Tornadoes can accompany tropical storms and hurricanes as
they move onto land.
Tornado Video
Birth of a Tornado
Tornado Video
Moore, OK – May 20, 2013 – F5
Tornado
Moore, OK – May 20, 2013 – F5
Tornado
Moore, OK – May 20, 2013 – F5