- Facts about Tornadoes and Twisters
- A tornado is a rapidly spinning tube of air that touches both the ground and a cloud above.
Tornadoes are sometimes called twisters.
Not all tornadoes are visible but their high wind speeds and rapid rotation often form a visible funnel of condensed water.
The Fujita Scale is a common way of measuring the strength of tornadoes. The scale ranges from F0 tornadoes that cause minimal damage through to F5 tornadoes which cause massive damage.
Most tornadoes have wind speeds less than 100 miles per hour (161 kilometres per hour).
Extreme tornadoes can reach wind speeds of over 300 miles per hour (483 kilometres per hour).
Most tornadoes travel a few miles before exhausting themselves.
Extreme tornadoes can travel much further, sometimes over 100 miles (161kilometres).
The Tri-State Tornado that traveled through parts of Missouri, Illinois and Indiana in 1925 left a path of destruction over 219 miles (352 kilometres) long.
The Tri-State Tornado was the deadliest tornado in US history, killing 695 people.
The USA averages around 1200 tornadoes every year, more than any other country.
The majority of these tornadoes occur in a geographically unique area nicknamed ‘Tornado Alley’.
US States most often hit by tornadoes include Texas, Kansas, Oklahoma and Florida.
In 1989 the deadliest tornado ever recorded in the world killed around 1300 people in Bangladesh.
In the southern hemisphere tornadoes usually rotate in a clockwise direction.
In the northern hemisphere tornadoes usually rotate in a counterclockwise direction.
A tornado that occurs over water is often called a waterspout.
Weather radars are used to detect tornadoes and give advanced warning.
Basements and other underground areas are the safest places to seek refuge during a Tornado. It is also a good idea to stay away from windows.
Precautions for School Bus Drivers.
Bus drivers should listen to radio weather bulletins as well as using their
two-way radios to stay in contact with the Bus Garage. The drivers should
listen for a:
Tornado Watch: Tornadoes are possible in your
area. Remain alert for approaching storms.
Tornado Warning: A tornado has been sighted or
indicated by weather radar. Warnings are issued for
counties and/or communities and include the tornado’s
location, direction, and speed. If the warning
is for your area, follow the safety plan developed by
the school district .
Remember, tornadoes occasionally develop in areas in which a severe
thunderstorm watch or warning is in effect. Remain alert to signs of an approaching
tornado or storm such as a dark, often greenish sky; wall cloud;
large hail; and/or loud roar, similar to a freight train. If any of these threatening
conditions exist, take immediate action. Occasionally, tornadoes
develop so rapidly that advance warning is not possible. Remain alert for
the signs of an approaching storm.
1. Upon first sighting a tornado, determine in which direction it is traveling
and whether it will hit you.
2. If the tornado is moving toward the area you are driving toward, do not continue in that direction.
Instead, either stop if the storm is very close, or retreat at right angles to the storm’s path if it is not
nearby. Do NOT attempt to outrun a tornado which is bearing down on your vehicle.
3. If there is a likelihood that the tornado will hit your vehicle, and there is no escape route available:
a. Evacuate the bus.
b. Take the students to the nearest ditch, depression, or ravine upwind (on the storm side) of
the bus far enough away from the bus so that bus will not roll over on them. Avoid areas with many trees.
c. Instruct the students to lie flat and to cover their heads with their arms.
Do not allow the students to take personal possessions other than coats and jackets. These items
could be used to cover their heads and bodies. Take only the first aid kit.
Do not take the students to an underpass. It is not known how safe an underpass is or how much
shelter it would provide from flying debris in a strong or violent tornado. Flying debris causes most of
the deaths and injuries in tornadoes. It is much safer for the students to be in a ditch.
4. If you are driving when you hear a tornado warning or spot a funnel and there is no time to move
the students to a ditch, have the students assume the protective position, remaining in their seats with
their heads below window level. Shut off the vehicle, except for the lights, and get under the dash
away from the door.
5. After the tornado has passed, look for further funnel clouds. If none are apparent, see to the safety
of your students. If the students are in a ditch, return them to the bus to avoid severe rain and hail
which often accompanies a tornado. Attend to the injured students. Notify authorities as soon as